A cassette grounding apparatus includes a plurality of first contacts provided on a cassette casing for accommodating an object to be grounded in such a manner that the contacts are exposed. Each of the first contacts is electrically connected to the object accommodated in the cassette casing. A second contact which is constituted by a spring member is provided on a cassette holder into which the cassette casing is loaded. The second contact is grounded and adapted to contact one of the first contacts on the cassette casing when it is loaded in the cassette holder, thereby grounding the object accommodated in the cassette casing. A third contact which is constituted by a spring member is further provided on the cassette holder. The third contact is connected to means for detecting a contact condition between the first and second contacts, and adapted to contact the other of the first contacts on the cassette casing when it is loaded in the cassette holder.