This crankshaft is provided with a journal part (J) as a rotational center axis, a pin part (P) eccentric relative to the journal part (J), a crank arm part (A) joining the journal part (J) and the pin part (P), and a counter weight part (W) integrated with the crank arm part (A), the pin part (P)-side surface of the crank arm part (A) having concave parts (10) formed along the inner sides of edge parts (11) on both sides running along the contours of this surface. This crankshaft can be made lightweight and can have improved torsional stiffness and bending stiffness.