The impeller is provided with a disk that rotates about an axis line, and a plurality of blades provided at intervals around the circumference of the disk. Defining the blade angle of the tip of each blade as a first blade angle, the tip has a constant-tip-angle area in which the first blade angle is constant from an inlet where fluid flows in toward an outlet side, and an increasing-tip-angle area that is continuous with the outlet side of the constant-tip-angle area and that has a gradually increasing first blade angle towards the outlet.