A cross flow fan including an impeller having at least two rings arranged with intervals in a fan rotation axis O direction and a plurality of blades that are arranged, between correlated rings, with intervals in a circumferential direction of the rings, in which the blade is divided into plural areas in the fan rotation axis O direction, and both ends adjacent to the rings are denoted as the blade-ring proximate sections and the center portion of the blade is denoted as the inter-blade-ring center section. The blade is formed such that the thickness of the inner peripheral blade end of the blade that is the inner peripheral end of the impeller is smaller in the inter-blade-ring center section than in the blade-ring proximate section.