An automatic transmission apparatus (1) for a vehicle includes: a shift lever (11) for changing the range of an automatic transmission (50); a position gate (13) which restricts the position of the shift lever (11) and which releases the restriction to allow the position of the shift lever (11) to be changed when an operation button (14) provided on the shift lever (11) is pressed; a torque sensor (30) which detects an operation force of the shift lever (11); and a motor (M) for power-assisting the operation of the shift lever (11) based on a detected value of the torque sensor (30), wherein, when the shift lever (11) is operated and brought into contact with the position gate (13), and the detected value of the torque sensor (30) is reversed to any one of a positive value and a negative value, a driving force of the motor (M) is limited to prevent the shift lever (11) from being power-assisted in a reversed direction.