The semiconductor thin film crystallization method comprises the step of forming a semiconductor thin film 14 over a substrate 10; the step of forming band-shaped portion 16 for blocking crystal growth of the semiconductor thin film in the semiconductor film or over the semiconductor film; and the step of causing an energy beam 18 of a continuous wave to scan in a direction intersecting the longitudinal direction of the portion for blocking crystal growth. The energy beam is caused to scan, intersecting the portion for blocking the crystal growth, whereby the crystal growth can be interrupted when the application region of the energy beam intersects the portions for blocking the crystal growth. Even when a solid semiconductor thin film which is not patterned in islands is crystallized, the semiconductor thin film of good crystals can be formed with high yields while the film is prevented from peeling.