An X-arm type window regulator according to the present invention comprises a lift arm, a lift arm bracket, an equalizer arm, and an equalizer arm bracket. Window glass is opened or closed as the lift arm of the window regulator is rotated. The lift arm comprises stress distributing convex parts which are formed close to a ring-shaped convex part disposed around a penetration hole in the center part of the lift arm, are formed at the base end side, and are formed at edge positions. The stress distributing convex parts distribute stress caused by a load from a tip end side of the lift arm.