In a device for locking a front door of a tape recorder including a front door (130) pivotably installed at the front surface of the tape recorder and locking unit for locking the front door, the locking unit is comprised of a pushing member, a first locking unit and a second locking unit. The pushing member (150) is installed in the front door protruding from the front side of the front door and pushed in contact with a tape cassette (100) being inserted. The first locking unit (170) is installed inside a housing (110) of the tape recorder and is for locking the front door, releasing the locking of the front door by interlocking with the pushing member when the tape cassette is inserted, and releasing the locking of the front door by interlocking with the tape cassette when the tape cassette is ejected. The second locking unit (190) is installed inside the housing and for locking the front door by interlocking with the tape cassette only when the tape cassette is loaded in the housing.
