The present invention provides a manufacturing method of a display device which can prevent the reduction of a size of a pseudo single-crystalline region having strip-like crystals in forming such a pseudo single-crystalline silicon region on a substrate. A step for forming pseudo single crystals having strip-like crystals on a preset region of a semiconductor film formed on a substrate includes a step for forming the pseudo single crystal by radiating an energy beam to a first region of the semiconductor film while moving a radiation position of the energy beam in a first direction, and a step for forming the pseudo single crystal by radiating the energy beam to a second region of the semiconductor film while moving a radiation position of the energy beam in a second direction opposite to the first direction. The first region and the second region set sizes thereof at a position where the radiation of the energy beam is finished smaller than sizes thereof at a position where the radiation of the energy beam is started. The second region includes a portion where the second region overlaps the first region and a portion where the second region does not overlap the first region.