An air conditioner comprising: a housing including an outlet; and a blade configured to open and close the outlet, the blade including: a body, a plurality of holes formed in the body, a first side extending in a first direction, a second side extending in a second direction, the first side being longer than the second side, a block area in which none of the plurality of holes are formed, and a rib coupled with the housing, wherein a number of the plurality of holes are disposed, respectively, along a first line extending in the first direction and a second line extending in the first direction, the second line spaced from the first line in the second direction, the number of the plurality of holes are disposed, respectively, on a first column extending in the second direction and a second column extending in the second direction, the second column spaced from the first column in the first direction, and the first column and the second column extend in zigzags, wherein the block area comprises a first block area formed in the first direction between the first line and the second line, and a second block area formed in the second direction between the first column and the second column, and the second block area comprises a plurality of bending portions bent in the first direction or in an opposite direction to the first direction, and wherein the rib is configured to protrude from the second block area in a third direction perpendicular to the first direction and the second direction without overlapping with the plurality of holes, and wherein the rib protrudes from an inside of the second block area and extends in the third direction in correspondence to the plurality of bending portions with respect to the first direction and the second direction. a housing including an outlet; and a blade configured to open and close the outlet, the blade including: a body, a plurality of holes formed in the body, a first side extending in a first direction, a second side extending in a second direction, the first side being longer than the second side, a block area in which none of the plurality of holes are formed, and a rib coupled with the housing, a body, a plurality of holes formed in the body, a first side extending in a first direction, a second side extending in a second direction, the first side being longer than the second side, a block area in which none of the plurality of holes are formed, and a rib coupled with the housing, wherein a number of the plurality of holes are disposed, respectively, along a first line extending in the first direction and a second line extending in the first direction, the second line spaced from the first line in the second direction, the number of the plurality of holes are disposed, respectively, on a first column extending in the second direction and a second column extending in the second direction, the second column spaced from the first column in the first direction, and the first column and the second column extend in zigzags, wherein the block area comprises a first block area formed in the first direction between the first line and the second line, and a second block area formed in the second direction between the first column and the second column, and the second block area comprises a plurality of bending portions bent in the first direction or in an opposite direction to the first direction, and wherein the rib is configured to protrude from the second block area in a third direction perpendicular to the first direction and the second direction without overlapping with the plurality of holes, and wherein the rib protrudes from an inside of the second block area and extends in the third direction in correspondence to the plurality of bending portions with respect to the first direction and the second direction.