Heat exchanger and refrigeration cycle device

A heat exchanger includes: a heat transfer pipe in which refrigerant flows; and a spiral groove formed at an inner peripheral surface of the heat transfer pipe. A height of an inner wall of the groove in a radial direction of the heat transfer pipe is equal to or greater than 0.1 [mm], and when a wetted edge length of the heat transfer pipe is S, an inclination angle between a pipe axis direction of the heat transfer pipe and a longitudinal direction of the groove in a section of the heat transfer pipe parallel with the pipe axis direction is 0, and a length of the heat transfer pipe is L, the inclination angle 0 is an acute angle, and a wetted area S x L/cosO of the heat transfer pipe satisfies S x L/cosO 0.5 [m2 ]. 231-2 231-1