To provide a piezoelectrically operating optical relay array which latches with liquid metal.

Provided is the optical relay array which uses liquid metal such as mercury as a switching mechanism and a latch mechanism. Further, disclosed is a piezoelectric optical relay array having one or more array elements. An array element includes a transparent mirror housing arranged at an intersection of two optical paths. Solid slag moves in a channel penetrating the transparent mirror housing by operating a piezoelectric element. The surface of the solid slag is wetted with the liquid metal to form a reflecting surface. The solid slag moves inside or outside the transparent mirror housing to select an optical path. When the solid slag is in the transparent mirror housing, an input optical signal is reflected by the reflecting surface of the liquid metal and a light signal which is not reflected passes through the transparent housing. The liquid metal sticks even on the surface of metal in the channel which can be wetted to form a latch mechanism.