An arm front surface 35 of an arm portion 34 of a tape cassette 30 includes an arm indicator portion adjacent to an exit 34A from which a tape is discharged. The arm indicator portion includes at least one aperture and indicates a tape type. A section of the tape is exposed between the exit 34A and regulating members 36 provided on the downstream side of the exit 34A in a tape feed direction. A person can easily identify the tape type by visually checking the arm indicator portion with the exposed tape. A platen holder 12 of a tape printer 1 has a plurality of arm detecting switches 210 at positions corresponding to the arm indicator portion of the tape cassette 30 installed in a cassette housing portion 8. The tape printer 1 detects the tape type based on on and off states of the arm detecting switches 210.
