A semiconductor device includes an interlayer insulating film formed on a semiconductor substrate to cover a lower electrode, a side-wall insulating film formed on a side wall of a contact hole formed through the interlayer insulating film to a depth reaching the lower electrode, a heater formed in the interior of the contact hole defined by the side-wall insulating film, and a phase-change film in contact with the top surface of the heater. The heater is in contact with the lower electrode at the bottom surface within the contact hole, and the top surface thereof is located at a lower level than that of the top surface of the side-wall insulating film. The top surface of the heater is located at a lower level than the top surface of the side-wall insulating film by an extent equal to or greater than a thickness of the phase-change film.