An extrusion die for use in production of a honeycomb molded body including a plurality of cells arranged in parallel with one another in a longitudinal direction with a cell wall therebetween, with the cell wall having a thickness of 0.21 mm or less, the extrusion die comprising: a first face; a second face formed opposite to the first face; a material supply section having first through holes extending from the first face to the second face; and a molding section having second through holes extending from the second face to the first face to communicate with the first through holes, wherein the second through holes viewed from the second face form slits in a grid shape, and each first through hole viewed from the first face is formed between adjacent intersections (15, 15a, 15b, 15c) of the slits viewed from the first face, the slits include outermost peripheral slits for molding an outermost peripheral wall of the honeycomb molded body, peripheral slits for molding cell walls of outermost peripheral cells located at an outermost peripheral region of the honeycomb molded body, and inner slits for molding cell walls of inner cells located more inward than the outermost peripheral cells, all projections of an inner grid surrounded by the inner slits viewed from the second face have the same shape that is a substantial rectangle, projections of a peripheral grid located at a region outside the projections of the inner grid excluding corners viewed from the second face each have a shape formed by chamfering or rounding two corners of the shape of the projection of the inner grid, with the chamfered or rounded corners adjacent to the outermost peripheral slits, and the area of each projection of the peripheral grid viewed from the second face is 60 to 80% of the area of each projection of the inner grid viewed from the second face. a first face; a second face formed opposite to the first face; a material supply section having first through holes extending from the first face to the second face; and a molding section having second through holes extending from the second face to the first face to communicate with the first through holes, wherein the second through holes viewed from the second face form slits in a grid shape, and each first through hole viewed from the first face is formed between adjacent intersections (15, 15a, 15b, 15c) of the slits viewed from the first face, the slits include outermost peripheral slits for molding an outermost peripheral wall of the honeycomb molded body, peripheral slits for molding cell walls of outermost peripheral cells located at an outermost peripheral region of the honeycomb molded body, and inner slits for molding cell walls of inner cells located more inward than the outermost peripheral cells, all projections of an inner grid surrounded by the inner slits viewed from the second face have the same shape that is a substantial rectangle, projections of a peripheral grid located at a region outside the projections of the inner grid excluding corners viewed from the second face each have a shape formed by chamfering or rounding two corners of the shape of the projection of the inner grid, with the chamfered or rounded corners adjacent to the outermost peripheral slits, and the area of each projection of the peripheral grid viewed from the second face is 60 to 80% of the area of each projection of the inner grid viewed from the second face.