An improved battery residual capacity meter or display device which is positioned on an electrically-assisted bicycle so as to enhance the visibility thereof. In addition, the battery residual capacity meter can measure residual battery capacity even when an electric motor associated with the bicycle is stopped. In one embodiment, the residual battery capacity meter includes a display unit having a plurality of lamps, a residual capacity measurement unit for measuring the residual battery capacity based on a voltage of a battery associated with the bicycle, and a display controller for controlling the illumination and flashing of the lamps so as to indicate a particular residual battery capacity measured by the residual capacity measurement unit. Further, the residual capacity measurement unit includes a drive mode measurement module for continuously measuring the residual battery capacity while the electric motor is operated in a drive mode, and a stop mode measurement module for measuring residual battery capacity after a predetermined time elapses from the moment the electric motor is stopped.