A pulse laser beam having a rectangular irradiation region is irradiated on the same point in a non-single crystal semiconductor film multiple times. The pulse laser beam has an energy profile in a longitudinal direction in the beam irradiation region as follows: (a) there are the first region having an energy density of Ea or higher and the second regions on both sides of the first region having an energy density of less than Ea, and (b) an energy density slope has an absolute value of 20 to 300 J/cm3 in a boundary region extending to 1 &mgr;m from the boundary line between the first and the second regions.