A crankshaft is provided with a journal section (J) that serves as a central axis of rotation, a pin section (P) that is eccentric with respect to the journal section (J), and a crank arm section (A) that connects the journal section (J) and the pin section (P). All or part of the crank arm section (A) integrally comprises a counterweight section. An edge section (11) follows the outline of the surface of the crank arm section (A) on the journal section (J) side thereof, and a recessed section (10) is formed along the edge section (11) on the inner side thereof. As a result, it is possible to decrease the weight of the crankshaft and improve torsional rigidity while improving bending rigidity.