Tape cassette loading device in a magnetic recording and/or reproducing apparatus

A tape cassette loading device comprises a cassette holder for accommodating and holding a tape cassette which is inserted therein, a guiding mechanism for guiding the cassette holder so that the cassette holder undergoes a predetermined movement, a driving mechanism which starts to operate when the tape cassette is inserted into the cassette holder, and a loading mechanism driven by the driving mechanism. The cassette holder is movable together with the inserted tape cassette between a cassette inserting position where the tape cassette is inserted and a predetermined loading position where a member of a recording and/or reproducing apparatus relatively enters within the tape cassette. This member is required to carry out recording and reproduction. The above predetermined movement includes in sequence a horizontal frontward movement of the cassette holder from the cassette inserting position, a subsequent obliquely upward movement of the cassette holder for avoiding the horizontal frontward movement from being interfered by the member, and a subsequent downward movement of the cassette holder to the predetermined loading position. The loading mechanism moves the cassette holder under guidance of the guiding mechanism to the predetermined loading position together with the tape cassette which is accommodated within the cassette holder.