Adjustment aid and laser welding device

The invention provides an adjustment aid and a laser welding device, which can quantify the deviation of an actual focus position relative to a designed focus position. The adjustment aid for adjusting a tool coordinate system of a galvanometer scanner is attached to the laser emission side of the galvanometer scanner. The adjustment aid is provided with: a light-receiving member having at least one flat light-receiving surface; and a connection member for connecting the light-receiving member to the galvanometer scanner. The light receiving member has a light receiving marking part on the light receiving surface, and is disposed so as to face the laser emission port of the galvanometer scanner so as to be spaced apart from the laser emission port by a predetermined distance. The light receiving marking part is used for quantizing the relative position difference between the actual light receiving position of the light emitted from the laser light emitting port and the reference lightreceiving position of the