A motor-driven compressor includes a compression mechanism. The compression mechanism includes a stationary scroll and a movable scroll. The movable scroll and the stationary scroll form a compression chamber. The motor-driven compressor has an electric motor accommodated in a motor chamber, a suction pressure zone, a discharge chamber, and an oil passage, which is connected either to the compression chamber or the discharge chamber. The electric motor includes a rotary shaft and drives the movable scroll via the rotary shaft. A main bearing located in the vicinity of the compression mechanism rotationally supports the rotary shaft. The rotary shaft has an in-shaft passage. The oil passage has a radial passage, which is directly connected to the in-shaft passage, and the in-shaft passage has an outlet, which opens to the motor chamber. The main bearing is exposed in the oil passage. The motor chamber is the suction pressure zone.