An anesthetic system including main unit (10) capable of not only supply of anesthetic gas but also performing of artificial respiration motion; introduction box (20) for anesthetic gas introduction wherein a small animal can be housed; anesthetic gas treating section (30) connected to the introduction box (20); and respiration circuit tube (50) with tube insertion part (53). The main unit (10) includes first outlet (10a), second outlet (10c), return orifice (10b) and accessway (17) linking the return orifice with the second outlet. Any anesthetic gas emitted from the first outlet (10a) is fed back through the respiration circuit tube (50) to the return orifice (10b), passes through the accessway (17) and is emitted from the second outlet (10c). The emitted gas passes through supply tube (60) and is fed to the introduction box (20).
