An oil separator for an air conditioner, which includes: a case having a cylinder portion, and a lid portion and a bottom portion respectively closing an upper side opening end and a lower side opening end of the cylinder portion; an inlet pipe which is connectable to a discharging outlet of a compressor and which penetrates the lid portion so that an end of the inlet pipe is located inside the case; an outlet pipe which is connectable to a condenser and which penetrates the lid portion so that an end portion of the outlet pipe is located inside the case and protrudes into the cylinder portion toward the bottom portion; and a mesh portion which is provided to the end of the inlet pipe.