The present invention relates to a production and a usage of a functional substance of a fine powder of nanometer size, and to an improved treatment device of the functional substance and an improved applied device of a functional product, further, to a weight reduction of a device using the functional substance and a production cost reduction. The functional product uses a functional product means in which a fine functional powder of nanometer size or a fine functional powder of nanometer size packed together using a coating material is made into a solid or granular membrane. A treatment device of a functional substance comprises: single or plural of treatment container means which is a pressure-resistant container provided with a flange, a jacket and a temperature control section; a hydrogen filling means having a deaerating device and a hydrogen storage and release device which are mounted on said pressure-resistance container; a heating and cooling device having a heating device and a cooling device which are mounted on each of said pressure-resistant container and said hydrogen storage and release device; and an electric control means for automatically controlling said treatment container, said hydrogen filling means and said heating and cooling means. A storage device for a functional product comprises a energy conversion and storage means for sealing and storing a functional product, which has been subjected to a reduction and a hydrogenation of a functional substance using natural or regenerable energy, in a waterproof container or bag. A molded product, a painting material, a coating material and a grouting material using said functional product comprises a catalytic means in which a material, a binder and a functional catalytic product are mixed and dispersed. A hydrogen solvent using said functional product comprises a hydrogen solution means in which a functional product of a hydrogenated functional substance is mixed with a granular, solid or viscous medicine, food or adhesive membrane material, or is filled in a container. A hydrogen utilization device using said functional product comprises: a hydrogen discharge means comprising a hydrogen generating container on which a functional product consisting of a functional hydrogenated substance is mounted; a hydrogen storage and release means comprising a hydrogen storage container using a hydrogen storage substance on which a heating device is attached; a hydrogen generating means for reacting said functional product of said hydrogen discharge means with liquid water to form a metal hydride and to generate a hydrogen gas from a hydrolysis; a row material water supply means for supplying the hydrogen gas generated by said hydrogen generating means to a hydrogen utilization body and applying water being compounded with oxygen to said hydrogen generating means; and an electric control means containing a detection system; wherein these means are constructed in a unit. A gas sensor using said functional product comprises: a composite element means comprising a gas reactant on which a measuring junction of a thermoelectric couple and a functional product are mounted; a detachable means for storing said composite element means in a detachable container; and an electric control means comprising an electric control unit consisting of a power source for controlling said composite element means, a Thomson effect control system and a Seebeck effect control system and the like. A secondary battery using said functional product comprises: an electrode means formed by using a functional product of an active substance and a low-temperature plastic coating material; and an unifying means bonding power generating elements comprising a negative electrode, a positive electrode and a separation membrane of said electrode means and covering the elements with an insulation membrane. A fuel cell or reversible fuel cell in which said functional product is used in a MEA (Membrane Electrode Assembly) plate comprises: a MEA (Membrane Electrode Assembly) plate means in which a MEA (Membrane Electrode Assembly) is formed on one side of a plate formed with a corrugated portion; a stacking means stacking a single body of said MEA (Membrane Electrode Assembly) plate, a MEA (Membrane Electrode Assembly) cassette in which two of said MEA (Membrane Electrode Assembly) plates are stacked, or the MEA (Membrane Electrode assembly) cassettes; and a sealing means covering said single body of MEA (Membrane Electrode Assembly) plate or said MEA (Membrane Electrode Assembly) cassette with a coating material, or, bonding the periphery of said stacked MEA (Membrane Electrode Assembly) cassettes, sealing and separating an inside of a positive electrode or a negative electrode and providing nozzles for a fluid of two passages. Accordingly, the present invention provides the following advantages. A fine powder of a metal hydride and a metal powder made by a reduction of a metal compound can be produced at low cost. Even when a fine powder of an activated functional substance is exposed in air for a long period, it is safe and firing and poisoning do not occur. This solves a conventional problem. And, the product can be easily mounted various devices with low cost. In addition, by producing magnesium hydride using natural or renewable energy, it makes possible to convert the energy into a high-density safe substance and to store and transport. Furthermore, a large quantity of hydrogen can be supplied to a hydrogen utilization body. And, a long-lived gas sensor, secondary cell and the like can be obtained.