To provide a label detector capable of preventing a label from being wastefully discharged without limiting the removing order even when a multi-row label with a plurality of labels temporarily is attached in the width direction of a strip-like mount.

The label detector comprises an upper reflection unit 30 arranged on the upper side of a label passing area, a light emission unit 21 arranged on the lower side of the label passing area, a light reception unit 22, and a lower side reflection unit 31. A sensor light projected from the light emission unit 21 is incident on the upper side reflection unit 30 at a predetermined angle. The sensor light incident on the upper reflection unit 30 is reflected by the upper reflection unit 30, and incident on the lower reflection unit 31. The sensor light incident on the lower reflection unit 31 is reflected by the lower reflection unit 31 and incident on the upper reflection unit 30. The sensor light incident on the upper reflection unit 30 is reflected by the upper reflection unit 30 and incident on the light reception unit 22.