a cassette handling apparatus having a main body part ; a cassette receiving part arranged to be able to assume first and second states relative to the main body part ; a moving member arranged to be in a first state when a portion of the cassette is loaded on the cassette receiving part and in a second state upon completion of cassette loading ; and a device for preventing the cassette receiving part from shifting from the first to the second state thereof when the moving member is in the first state thereof and for allowing the cassette receiving part to shift from the first to the second state thereof when the moving member is in its second state , whereby the cassette can be reliably prevented without fail from being used in an incompletely loaded condition on the cassette receiving part .