Abstract: An image forming apparatus includes a sheet feeding cassette, a cassette attachment part, and a sensor. The sensor is switched in a cassette detection state and a cassette non-detection state. The sheet feeding cassette includes a detected piece, a pressure piece, and a lock receiving part. The detected piece switches the sensor to the cassette detection state and to the cassette non-detection state. The presser piece is provided integrally with the detected piece. The lock receiving part supports the presser piece movably. The cassette attachment part includes a locking member. When the sheet feeding cassette is attached to the attachment part, the detected piece switches the sensor from the cassette non-detection state to the detection state to enable a sheet feeding operation from the sheet feeding cassette, and the pressure piece interferes with the locking member to cause the locking member to be engaged with the lock receiving part.