A rotor for a rotating electric machine has a core body and a magnet. The core body has a through-hole, a first polar portion, and a second polar portion. The first polar portion and the second polar portion are alternately arranged in the circumference direction. The magnet is disposed on the core body at a position corresponding to the first polar portion or the second polar portion. The through-hole has an arc-shaped surface having a first curvature radius. The first polar portion has an arc-shaped surface having a second curvature radius. The second polar portion has an arc-shaped surface having a third curvature radius. The first curvature radius is larger than or equal to the second curvature radius. The first curvature radius is larger than or equal to the third curvature radius.