A method of manufacturing a thin-film magnetic head structure comprises the steps of preparing an insulating layer 10; forming a first resist layer 51 provided with a first slit pattern 51a corresponding to a very narrow groove part and a second slit pattern 51b corresponding to a temporary groove part integrally extending from the very narrow groove part along outer edges of a main depression onto the insulating layer 10; etching the insulating layer 10 while using the first resist layer 51 as a mask; eliminating the first resist layer 51; forming a second resist layer having an opening pattern corresponding to the main depression onto the insulating layer 10; and etching the insulating layer 10 while using the second resist layer as a mask.