In an actuator, an unnecessarily large load is prevented from being applied to a shaft and a workpiece. There are included a force sensor, an output of which is according to a force applied to a connecting member connected to the shaft, an amplifier that amplifies the output of the force sensor, and a low-pass filter, and a load applied to the shaft is detected based on an output from the amplifier until the shaft or a member associated with the shaft comes in contact with another member, and thereafter, the load applied to the shaft is detected based on an output from the low-pass filter.