Cartridge holder with a cartridge height position locking mechanism accommodating tape cartridges of differing tape widths

A cartridge holder is disclosed that includes a cartridge supporting member that supports an inserted cartridge corresponding to a first cartridge or a thicker second cartridge; a cartridge upper face holding member that is normally positioned at a first height position for holding down the first cartridge; a cartridge upper face holding member supporting mechanism configured to move the cartridge upper face holding member with respect to the cartridge supporting member; and a lock mechanism configured to lock the cartridge upper face holding member in the first height position. The cartridge supporting member and the cartridge upper face holding member define a cartridge accommodating space. The lock mechanism remains locked when the first cartridge is inserted, and unlocks when the second cartridge is inserted. When the second cartridge is inserted, the cartridge upper face holding member is raised, and the size of the cartridge accommodating space is changed.