Abstract: A cartridge loading apparatus is provided with a pair of locking devices for locking a cartridge received in a housing of the apparatus under a prescribed force. Each locking device includes a locking lever which is rotatable between a release position where the cartridge is set freely movable and a locking position where the locking lever engages a recess formed on each lateral side face of the cartridge, a reverse insertion prevention lever rotatable about the same shaft as the rotating shaft of the locking lever, a first spring for biasing the locking lever and the reverse insertion prevention lever to come close to each other, and a second spring for biasing the locking lever to the release position while the locking lever and reverse insertion prevention lever are biased to come close to each other. The locking lever is biased by the first spring from the release position to the locking position upon engagement between the reverse insertion prevention lever and the cartridge inserted in the housing.