A lens unit consists of a plurality of lens frames, a stepping motor, and a driving control unit. The plurality of lens frames for holding an imaging optical system lies in a lens barrel and moves over a stowage interval and a zoom interval. The stowage interval is an interval between a position of stowage at which the lens frames are stowed and a ready-to-image position at which imaging is enabled. The zoom interval is an interval over which the ready-to-image position exists and a power varying action is executed. The stepping motor moves the plurality of lens frames. During execution of a thrusting action or storing action, the driving control unit drives and controls the stepping motor in a first driving mode. The thrusting action is executed for moving the plurality of lens frames from the position of stowage to the ready-to-image position. The stowing action is executed for moving the lens frames from any position within the zoom interval to the position of stowage. During execution of a zooming action for moving the lens frames over the zoom interval, the driving control means unit drives and controls the stepping motor in a second driving mode in which a lower current is used than in the first driving mode.