A cartridge chucking apparatus capable of stably and correctly restricting the position of a cartridge with an improved reliability and precision. A cartridge is provided with a circle hole and an elongated hole as reference holes for restricting an in-plane position of the cartridge. The cartridge chucking apparatus has: a loading chassis having projections for holding the cartridge and restricting the position in the height direction and support shafts for supporting the loading chassis while it is raised or lowered; a base chassis having reference planes for squeezing the cartridge with the projections at a recording/reproducing position of the loading chassis to restrict the position in the height direction and positioning pins formed on the reference planes for being inserted into the reference holes to restrict an in-plane position of the cartridge; and elastic members for energizing the loading chassis so that first the positioning pin is inserted into the circle hole of the cartridge.