A method for surface treating a thermoplastic resin shaped article is disclosed, which comprises irradiating a surface of the shaped article with an ultraviolet light having a wavelength of 300 nm or less, said shaped article being obtained from a resin composition comprising (I) 100 parts by weight of a resin comprising from 5 to 100% by weight of a polyphenylene ether resin, a mixture of a polyphenylene ether resin and a styrene resin; or a graft copolymer of a polyphenylene ether resin and styrene and from 95 to 0% by weight of at least one thermoplastic resin selected from the group consisting of a polyamide resin and a saturated polyester resin; (II) from ) 0 to 50 parts by weight of a rubbery substance; (III) from 0 to 50 parts by weight of an inorganic filler and/or glass fibers; and (IV) from 0 to 10 parts by weight of at least one compatibilizer for improving the compatibility between said polyphenylene ether resin and said polyamide resin and/or saturated polyester resin. A method for coating said shaped article is also disclosed.