To provide a method for mercy killing of an animal comprising minimizing pain until the animal loses consciousness and the pain during the killing by efficiently using an anesthetic in a volume suitable for each objective animal in the method for mercy killing comprising anesthetizing the animal and then subjecting the animal to death from suffocation and to provide an apparatus for mercy killing for the animal.

The method for mercy killing of the animal is carried out as follows. The animal is housed in a treatment chamber of a prescribed volume and an anesthetic gas evaporated at a prescribed rate with an anesthetic liquid evaporator is supplied into the treatment chamber to make the animal inhale the anesthetic gas and thereby anesthetize the animal. The interior of the treatment chamber is then kept in a state of oxygen deficiency and the animal is subjected to mercy killing. Furthermore, the apparatus for mercy killing for the animal is provided. Thereby, the pain of the animal to be killed to the death can be suppressed by using the apparatus for mercy killing for the animal.