A half bearing for supporting a crank shaft of an internal combustion engine is provided. The half bearing having a main semi-cylindrical part, two crush reliefs, and two transition regions. Each crush relief has a depth from a imaginary plane at a circumferential end surface of the half bearing greater than a depth from the imaginary plane at a connecting position between each crush relief and the transition region. A plurality of circumferential grooves extend in a circumferential direction in the main semi-cylindrical part along their entire length in the circumferential direction, and the plurality of circumferential grooves extend also in the transition region continuously.