A negative pressure type actuator (4) includes a diaphragm (43), an output shaft (44) extending toward an opposite side of a negative pressure chamber (410), a stopper (46) provided such that the output shaft penetrates the stopper, and a stopper engagement portion (47) fixed to the output shaft. The stopper has a first contact surface (462) configured to contact a stopper engagement portion, and the stopper engagement portion has a second contact surface (471). The first contact surface (462) is formed in an arc shape in a section including the axis (X2) of the output shaft, and the second contact surface (471) is, in the section including the axis of the output shaft, formed in an arc shape with the same curvature as that of the first contact surface.