A method of manufacturing a laser welded steel pipe by forming a steel strip into a cylindrical open pipe and performing laser welding on edges that includes: emitting two laser beams along the edges from an upper surface side of the open pipe, the two laser beams being transmitted through different optical fibers with in-focus spot diameters exceeding 0.3 mm; emitting leading and trailing laser beams each inclined toward a direction in which welding proceeds at an incident angle with respect to a direction perpendicular to an upper surface of the open pipe; setting the incident angle of the leading laser beam to be larger than the incident angle of the trailing laser beam; and setting a gap between a center point of the leading laser beam and a center point of the trailing laser beam on a back surface of the open pipe to 1 mm or larger.