A tightening tool such as a torque wrench is provided in which electric power can be fed to an electronic circuit with eliminating the need for a battery and achieving daily maintenance-free. In the tightening tool, when a tightening torque has reached a set torque value and a torque limiter is actuated, an electronic circuit unit that has obtained a detection signal outputted from a torque limiter actuation detection unit outputs a tightening completion signal. The tightening tool has a power generation unit for feeding electric power to the electronic circuit unit at least during the actuation of the torque limiter. The power generation unit performs photovoltaic power generation, electromagnetic induction power generation, power generation by conversion from mechanical energy into electrical energy, or temperature difference power generation.