An extremely small micro-relay having such a mechanical contact mechanism that it becomes smaller in resistance when the contact is turned on and has an excellent vibration resistance, frequency characteristic, and insultating property is constituted in such a way that a piezoelectric element (24) or heater layer (27) is provided on a thin plate-like single-crystal substrate (21) and a mobile piece (20) carrying a traveling contact (25) on one surface is supported on a base (11) while both ends of the piece (20) are fixed to the base (11) so that the traveling contact (25) can be brought into contact with or separated from a pair of fixed contacts (38 and 39) faced to the contact (25) when the piece (20) is bent by the action of the piezoelectric element (24) or the heater layer (27).
