To display the remaining usable time of a battery accurately.

The video camera 101 includes a liquid crystal monitor 102 and a charging microcomputer 103. The charging microcomputer 103 includes a battery residual capacity detection part 13a, a timer 13b, and a usable time calculation part 13c. The usable time calculation part 13c (i) calculates a remaining usable time based on a value concerning the residual capacity of the battery 201 detected by the battery residual capacity detection part 13a and a value concerning consumption current of the video camera 101 in a period from the start of the operation of the video camera 101 using the battery 201 until the remaining usable time of the battery 201 reaches at a predetermined threshold time, and (ii) calculates a remaining usable time based on the operation time measured by the timer 13c in a period until the remaining usable time becomes zero after the remaining usable time is less than a predetermined threshold time.