To provide a simple and low-cost waste liquid treatment apparatus which can forcibly eliminate bubbles generated and accumulated when waste liquid is heated and concentrated, and makes the deterioration of waste liquid treatment capacity of the apparatus small due to a small temperature drop at the bubble elimination.

In the waste liquid treatment apparatus where the waste liquid E stored in a treatment tank 1 is heated by a heating means 3 to be evaporated and concentrated, an air sucking means 4 and an air blowing means 6 which forcibly discharge evaporated material generated from the waste liquid E quickly to the outside of the treatment tank 1 are installed. The air sucking means 4 or the air blowing means 6 uses blowing air pressure to introduce outside air to the liquid surface of the waste liquid E or to blow air thereto, thereby forcibly eliminating the bubbles B accumulated on the liquid surface of the waste liquid E.