Firstly, an upper base material is disposed above a lower base material. Secondly, a laser beam is irradiated so that an area irradiated with a laser beam at a time of melting start is formed on only an upper surface of the upper base material or on only both the upper surface and an end surface of the upper base material, whereby the end surface of the upper base material and the lower base material are fillet welded. With the end surface as a reference, a side the upper surface and the lower surface are positioned is a first side, and an opposite side of the first side is a second side. The laser beam is set such that an intensity of the laser beam is lower toward the second side from the first peak area within the irradiation area of the laser beam.