A fuel cell comprising: a membrane electrode gas diffusion layer assembly, a frame member disposed around the membrane electrode gas diffusion layer assembly, and a pair of separators (110, 120) stacked on the frame member to sandwich the membrane electrode gas diffusion layer assembly and the frame member, wherein the separators (110, 120) include separator-side manifolds; wherein the frame member includes a skeleton connecting to the membrane electrode gas diffusion layer assembly, an opening for housing the membrane electrode gas diffusion layer assembly, frame member-side manifolds aligned and disposed to communicate with the separator-side manifolds, and a fluid introduction and derivation site between the opening and the frame member-side manifolds; wherein the fluid introduction and derivation site includes convexities to form a flow path for delivering a fluid in a horizontal direction of the frame member; wherein a thickness of the convexities is larger than a thickness of the skeleton, characterized in that: the skeleton and fluid introduction and derivation site of the frame member are composed of resin; the fluid introduction and derivation site and the skeleton are composed of members that are separable from each other, and the frame member includes an overlap region where at least a part of one surface of the skeleton and at least a part of the fluid introduction and derivation site overlap; and a vicinity site of the frame member-side manifolds of the convexities of the fluid introduction and derivation site, is in a form following a flange in the vicinity of the separator-side manifolds of the separators (110, 120). a membrane electrode gas diffusion layer assembly, a frame member disposed around the membrane electrode gas diffusion layer assembly, and a pair of separators (110, 120) stacked on the frame member to sandwich the membrane electrode gas diffusion layer assembly and the frame member, wherein the separators (110, 120) include separator-side manifolds; wherein the frame member includes a skeleton connecting to the membrane electrode gas diffusion layer assembly, an opening for housing the membrane electrode gas diffusion layer assembly, frame member-side manifolds aligned and disposed to communicate with the separator-side manifolds, and a fluid introduction and derivation site between the opening and the frame member-side manifolds; wherein the fluid introduction and derivation site includes convexities to form a flow path for delivering a fluid in a horizontal direction of the frame member; wherein a thickness of the convexities is larger than a thickness of the skeleton, characterized in that: the skeleton and fluid introduction and derivation site of the frame member are composed of resin; the fluid introduction and derivation site and the skeleton are composed of members that are separable from each other, and the frame member includes an overlap region where at least a part of one surface of the skeleton and at least a part of the fluid introduction and derivation site overlap; and a vicinity site of the frame member-side manifolds of the convexities of the fluid introduction and derivation site, is in a form following a flange in the vicinity of the separator-side manifolds of the separators (110, 120). the skeleton and fluid introduction and derivation site of the frame member are composed of resin; the fluid introduction and derivation site and the skeleton are composed of members that are separable from each other, and the frame member includes an overlap region where at least a part of one surface of the skeleton and at least a part of the fluid introduction and derivation site overlap; and a vicinity site of the frame member-side manifolds of the convexities of the fluid introduction and derivation site, is in a form following a flange in the vicinity of the separator-side manifolds of the separators (110, 120).