After gate insulating films, gate electrodes, and n+ type semiconductor regions and p+ type semiconductor regions for source/drain are formed, a metal film and a barrier film are formed on a semiconductor substrate. And a first heat treatment is performed so as to make the metal film react with the gate electrodes, the n+ type semiconductor region, and the p+ type semiconductor region, thereby forming a metal silicide layer formed of a monosilicide of a metal element forming the metal film. After that, the barrier film and the unreacted metal film are removed, and then a second heat treatment is performed to stabilize the metal silicide layer. The heat treatment temperature is made lower than a temperature at which a lattice size of a disilicide of the metal element and that of the semiconductor substrate become same.