Abstract: Disclosed is a power generating apparatus using a hammer comprising: a main body including a base body in which an operating fluid is stored, a first inner connecting rod provided to be movable to one side of the base body, and a spring provided at the other side of the base body; a hammer portion of which one side is rotatably coupled to the main body to hit the first inner connecting rod and the other side is connected to the spring; a hammer driving portion which hits the first inner connecting rod by the hammer portion to supply power; a crankshaft portion which rotates by receiving a force for hitting the hammer portion by the hammer driving portion; and a power transmission portion which is connected to the crankshaft portion to rotate together with the crankshaft and connected to a power generator.