Provided is a muffler for an air-conditioning apparatus, which is compact and has a small pressure loss, and an air-conditioning apparatus including the same. The muffler for an air-conditioning apparatus including a muffler main body which has small diameter portions on an inlet side and an outlet side, the small diameter portions having inner diameters smaller than an inner diameter of a central portion of the muffler main body, an inlet pipe connected to the small diameter portion on the inlet side of the muffler main body; and an outlet pipe connected to the small diameter portion on the outlet side of the muffler main body. The inlet pipe is inserted into the muffler main body, and has a distal end positioned at a center of a length from an inlet to an outlet of the muffler main body. The distal end side of the inlet pipe inserted into the muffler main body has an inner diameter smaller than an inner diameter of the inlet pipe on an upstream of the distal end side.