Recording and/or reproducing apparatus and recording medium cartridge holder

A recording medium cartridge holder in which a recording medium cartridge containing a recording medium and having a flat cartridge case of rectangular shape having a long side and short side, is inserted with the long side directed forwardly in an insertion direction, said recording medium cartridge holder comprising:

• a main support portion;
• a carrying portion, supported on said main support portion so as to be movable from a standby position to a withdrawal position, for withdrawing said recording medium cartridge held at said standby position to said withdrawal position;
• a lock portion for locking said carrying portion at said standby position;
• a biasing spring for biasing said lock portion toward a locking position;
• and
• an insertion restricting portion for prohibiting passing of said recording medium cartridge inserted in an orientation other than a predetermined orientations,
• wherein said lock portion is arranged directly above said insertion restricting portion, and
• wherein said lock portion releases the locking of said carrying portion by said recording medium cartridge passing through said insertion restricting portion.