An impeller includes a disk-shaped portion and rotor blades. The rotor blades include first rotor blades which includes a first curvature portion and second curvature portions. A center of a radius of curvature of the first curvature portion is on a first side. A center of a radius of curvature of each second curvature portion is on a second side. The radius of curvature of the second curvature portion radially outward is greater than the radius of curvature of the second curvature portion radially inward. The rotor blades include second rotor blades each of which is circumferentially between adjacent ones of the first rotor blades. Each second rotor blade includes third curvature portions. A center of a radius of curvature is on the second side. The radius of curvature of the third curvature portion radially outward is greater than the radius of curvature of the third curvature portion radially inward.