A motorman's cab display system includes a motorman's cab display apparatus that can automatically adjust display luminance of a display device without using an illuminance sensor. The motorman's cab display apparatus determines, based on location information of a train transmitted from a train information control system, whether the train is traveling in a tunnel, sets, when determining that the train is traveling in the tunnel, as the luminance of a display screen, luminance for inside of tunnel set in advance, and sets, when determining that the train is traveling outside the tunnel, as luminance of the display screen, luminance information for outside of tunnel set in advance. A display control method for motorman's cab display apparatuses includes: calculating a traveling location of the train; and adjusting the luminance of the display screen according to the luminance information output from a luminance determining unit.