This invention provides a heat transfer device which can improve its heat transfer performance in a heat exchanger with a flow rate of heat carrier fluid being set at a relatively low velocity, while restricting increase in pressure loss of the fluid flow. Plural longitudinal vortex generator winglets (10) are arranged in a spanwise direction on each side of the heat transfer object (T). The winglets on each side are oriented substantially in the same direction for deflecting the fluid to the same direction and conducting the fluid to an area behind the object. Each of the winglets has a configuration gradually decreasing in its height toward an upstream side of a flow of the fluid. Longitudinal vortices are produced behind the winglets by the fluid flowing rearward beyond the winglets.