A method for manufacturing a liquid-ejecting head that comprises an ejection-element section that ejects liquid and a liquid-supply section in which a liquid path for guiding the liquid to the ejection-element section is formed; wherein a main mold, and a die slide mold that can slide inside the main mold and in which a mold for forming a first part of the liquid-supply section and a mold for forming a second part of the liquid-supply section are arranged in a direction of the slide are prepared; the method including: a first molding process for forming the first part and the second part by injecting resin into the mold for forming the first part and into the mold for forming the second part with the main mold in a closed state; a sliding process for sliding the die slide mold and positioning and aligning the first part and the second part in the direction of the slide; and a second molding process for forming the liquid-supply section by bringing the first part and the second part into contact by inserting a convex section of the second part into an opening in the first part, and then injecting resin for connecting the first part and the second part together; wherein in the second molding process, a distance between an area where the resin is injected and the opening is larger than a distance between an inner wall surface of the opening and an outer wall surface of the convex section. a main mold, and a die slide mold that can slide inside the main mold and in which a mold for forming a first part of the liquid-supply section and a mold for forming a second part of the liquid-supply section are arranged in a direction of the slide are prepared; the method including: a first molding process for forming the first part and the second part by injecting resin into the mold for forming the first part and into the mold for forming the second part with the main mold in a closed state; a sliding process for sliding the die slide mold and positioning and aligning the first part and the second part in the direction of the slide; and a second molding process for forming the liquid-supply section by bringing the first part and the second part into contact by inserting a convex section of the second part into an opening in the first part, and then injecting resin for connecting the first part and the second part together; wherein a first molding process for forming the first part and the second part by injecting resin into the mold for forming the first part and into the mold for forming the second part with the main mold in a closed state; a sliding process for sliding the die slide mold and positioning and aligning the first part and the second part in the direction of the slide; and a second molding process for forming the liquid-supply section by bringing the first part and the second part into contact by inserting a convex section of the second part into an opening in the first part, and then injecting resin for connecting the first part and the second part together; wherein in the second molding process, a distance between an area where the resin is injected and the opening is larger than a distance between an inner wall surface of the opening and an outer wall surface of the convex section.