A cross-flow fan that is made of resin, the cross-flow fan comprising: a first fan block including a disc-shaped or annular first support plate, plural first blades having first one-side distal ends connected to the first support plate, and a first outer peripheral ring having a first ring portion that interconnects outer ends of the plural first blades in the neighborhood of first other-side distal ends of the plural first blades located on the opposite side of the first one-side distal ends; and a second fan block including a disc-shaped or annular second support plate, plural second blades having second one-side distal ends connected to the second support plate, and a second outer peripheral ring having a second ring portion that interconnects outer ends of the plural second blades in the neighborhood of second other-side distal ends of the plural second blades located on the opposite side of the second one-side distal ends, wherein the first fan block and the second fan block are joined together; and the second other-side distal ends of the plural second blades are joined to the first support plate, and the first support plate and the second outer peripheral ring are disposed in close proximity to each other, wherein the first support plate has a down-step portion at which the section of the first support plate corresponding to the second outer peripheral ring is sunken below the section of the first support plate corresponding to the inner peripheral side of the second outer peripheral ring, and the second outer peripheral ring enters the down-step portion, thereby reducing the longitudinal direction thickness with which the first support plate and the second outer peripheral ring lie on top of each other, characterized in that: the down-step portion of the first support plate is sunken deeper than the longitudinal direction thickness of the second outer peripheral ring in the longitudinal direction. a first fan block including a disc-shaped or annular first support plate, plural first blades having first one-side distal ends connected to the first support plate, and a first outer peripheral ring having a first ring portion that interconnects outer ends of the plural first blades in the neighborhood of first other-side distal ends of the plural first blades located on the opposite side of the first one-side distal ends; and a second fan block including a disc-shaped or annular second support plate, plural second blades having second one-side distal ends connected to the second support plate, and a second outer peripheral ring having a second ring portion that interconnects outer ends of the plural second blades in the neighborhood of second other-side distal ends of the plural second blades located on the opposite side of the second one-side distal ends, wherein the first fan block and the second fan block are joined together; and the second other-side distal ends of the plural second blades are joined to the first support plate, and the first support plate and the second outer peripheral ring are disposed in close proximity to each other, wherein the first support plate has a down-step portion at which the section of the first support plate corresponding to the second outer peripheral ring is sunken below the section of the first support plate corresponding to the inner peripheral side of the second outer peripheral ring, and the second outer peripheral ring enters the down-step portion, thereby reducing the longitudinal direction thickness with which the first support plate and the second outer peripheral ring lie on top of each other, characterized in that: the down-step portion of the first support plate is sunken deeper than the longitudinal direction thickness of the second outer peripheral ring in the longitudinal direction.