A cross-flow fan includes a plurality of fan blades circumferentially spaced from each other. The fan blade has an inner edge portion on the radially inner side, and an outer edge portion on the radially outer side. A blade surface extends between the inner edge portion and the outer edge portion. The blade surface includes a pressure surface on the rotation direction side of the fan and a suction surface on the opposite side. In cross-section orthogonal to the rotation axis of the fan, the fan blade has a concave portions formed at the pressure surface and the suction surface. A plurality of concave portions are formed at pressure surface. Side fan provides excellent blowing capacity. Also disclosed are a molding die for use in production of the cross-flow fan, and a fluid feeder provided with the cross-flow fan.