A ferromagnetic tunnel junction element to produce a high ratio of magnetoresistance at finite voltages including the element operating voltage, and a device provided therewith such as tunnel magnetoresistive head, magnetic head slider, and magnetic disk drive. The ferromagnetic tunnel junction element has a laminate structure of ferromagnetic layer/metallic layer/insulating layer/metallic layer/ferromagnetic layer. (The metallic layer is one atom thick or two atoms thick.) The metallic layer and insulating layer have the crystalline regularity. The element is capable of detecting magnetism with its high magnetoresistivity, about three times that of conventional elements, at finite voltages. This element makes it possible to realize a highly sensitive magnetoresistive head. The magnetic head is used for the magnetic head slider which realizes a magnetic disk drive capable of reproducing magnetic information with high sensitivity.