A thermal-type infra-red ray solid-state image sensor includes at least one device for detecting infra-red ray, wherein the device is comprised of a substrate including a signal-readout circuit, a contact electrode formed on the substrate and electrically connected to the signal-readout circuit, a diaphragm spaced away from and above the substrate, a support supporting the diaphragm such that the diaphragm floats above the substrate, and being composed of electrically conductive material to electrically connect the contact electrode to the diaphragm, and a hood formed on the diaphragm for preventing infra-red ray from being radiated to the support, absorbing the infra-red ray, and transferring heat resulted from the thus absorbed infra-red ray, to the diaphragm. The hood is comprised of a sidewall standing on the diaphragm, and an upper plate extending inwardly of the sidewall from an upper edge of the sidewall, the upper plate being formed with an opening.