Three-dimensional (3D) glasses according to the present disclosure are interconnected to a 3D display apparatus and include: a glass unit, a glass driving unit which drives the glass unit, an infrared (IR) sensor unit which receives a sync signal transmitted from the 3D display apparatus, a window unit which, when the 3D glasses are directed to the 3D display apparatus, transmits the sync signal to the IR sensor unit and transmits external IR light, incident from a direction different from the direction of the 3D display apparatus, away from the IR sensor unit, and a controlling unit which controls the glass driving unit based on the sync signal.