A manufacturing method of a pressure sensor that includes a pressure detector having a bottomed cylindrical member with a bottom including a thin-wall portion and a strain detecting mechanism provided on one side of the bottom for detecting a strain of the bottom and a pressure-introducing joint for introducing the fluid to be measured into the bottomed cylindrical member is provided. The method includes: first welding for butt-welding an end of the cylindrical portion of the bottomed cylindrical member and an end of the pressure-introducing joint; and second welding for welding the pressure-introducing joint in parallel to a first weld bead formed by the first welding.