Abstract: A magnetic recording/reproduction apparatus is disclosed which has a first state in which a tape cassette is placed on a chassis and a second state which includes a PLAY mode, a REV mode and a STOP mode. The apparatus comprises: a reel base rotatably mounted on the chassis via a shaft and engaging with a reel which holds the magnetic tape wound thereon in the tape cassette; a tension post allowing the magnetic tape to pass around a periphery thereof in the second state; and a tension arm supporting the tension post at a fixed position of the tension arm, the tension arm being swingably mounted on the chassis, the reel base including a drum portion rotating integrally with the reel base. The apparatus further comprises: a tension band having a center portion passing around the drum portion and one end swingably held by the tension around the arm; and a tension band regulating arm movably supported by the chassis, the tension band regulating arm holding the other end of the tension band.