Abstract: The invention provides: (1) a modified hydrogenase obtained by removing electron-transfer sites from a hydrogenase constituted of: active subunits including active sites having a hydrogen oxidization-reduction activity; and electron-transfer subunits having the electron-transfer sites through which electrons are transferred between the active sites and the outside of the hydrogenase; (2) a modified hydrogenase obtained from a hydrogenase, wherein when the hydrogenase is isolated from bacteria that produces the hydrogenase, a process for exposing the hydrogenase to an oxygen atmosphere is executed; (3) an enzymatic electrode made of at least one of the foregoing modified hydrogenases; and (4) a hydrogenase modification method including: a step of isolating from hydrogenase-producing bacteria; and a step of removing the electron-transfer sites of the electron-transfer subunits from the hydrogenase by exposing the hydrogenase to an oxygen atmosphere.