Abstract: A power-operated tape measure includes an annular reel pivotally mounted on a fixing shaft in a case, a tape wound on the annular reel, a hook at one end of the tape extending out of the case through an outlet of the case. A motor respectively drives the annular reel and a large wheel for sending the tape via a gear train. A control circuit includes the motor, a power supply unit and a control switch controlling the motor for direct and reverse turning. A button member at the bottom of the case that can float upwards and downwards, inside which a small wheel is pivotally fixed to engage with the large wheel for sending the tape. The control switches control the extending of the tape and the withdrawal of the tape, the switch controlling the extending of the tape engaging the inside part of the button member.