An impeller with a disc that rotates about an axis, and blades a plurality of which are disposed in the circumferential direction of the disc with intervals therebetween. A defined blade angle of the blade has a prescribed gradual increase region and gradual decrease region from the center towards the outside, and at the center of an inflection region of the gradual increase region and of the gradual decrease region, provided is a partial gradual decrease region having a smaller blade angle decrease amount than the blade angle increase amount of the gradual increase region.