An electromechanical transducer (1) has a pressurizing chamber (21) and a side-chamber (23) formed in a plate (11). On a driven film (13) forming the upper wall surface (21a) of the pressurizing chamber (21) and the side-chamber (23), a lower electrode (33), a driving member, and an upper electrode (35) are formed in this order. The driving member is composed of an operation section (31p) located over the pressurizing chamber (21), and an extended section (31a) extending from the operation section (31p) to over the side-chamber (23). The side-chamber (23) has a smaller width than the pressurizing chamber (21) in a second direction perpendicular to a first direction in which the side-chamber (23) is located beside the pressurizing chamber (21). The extended section (31a) of the driving member has a smaller width than the side-chamber (23) in the second direction.