A rear gate opening and closing apparatus includes a gas stay for biasing a rear gate in an opening direction, a motor for actuating to open or close the rear gate, a clutch for connecting or disconnecting the motor with the rear gate, an encoder for detecting the position of the rear gate, an operating switch for operating an opening and closing motion of the rear gate, and a control means for controlling the motor and clutch to automatically open and close the rear gate. The opening and closing speed of the rear gate is controlled based on a detection signal of the encoder.