Disclosed is a laser-transmissible resin composition for laser welding having 100 parts by weight of a thermoplastic resin, and 0.01 to 3 parts by weight of titanium oxide that has a density of at least 4 g/cm.sup.3 and an average particle size of 100 to 400 nm; and the resin composition exhibits a whitish hue of white, gray or tint color. Also disclosed is a method for laser welding that includes piling a resin workpiece that is at least partly capable of laser-absorption onto a laser-transmissible resin workpiece that is molded out of the laser-transmissible resin composition, and irradiating a laser beam thereto to weld thermally.