The present invention relates to a method of manufacturing a semiconductor device using a substrate including an organic low dielectric constant film containing a silicon, a carbon, an oxygen, and a hydrogen, with a resist pattern being formed on an upper layer side of the low dielectric constant film. The method comprising: an etching step in which the low dielectric constant film is etched by a plasma; an ashing step following to the etching step, in which the resist pattern is ashed by a plasma that is rich in oxygen radicals in such a manner that a relative dielectric constant of the low dielectric constant film can become 5.2 or more; and a recovering step following to the ashing step, in which an organic gas is supplied to the low dielectric constant film so as to recovery a damage of the low dielectric constant film caused by the plasma.