An anesthesia device configured to measure the hydrogen concentration in an anesthesia gas containing a hydrogen gas includes: an anesthesia gas preparation circuit configured to generate anesthesia gas by mixing an air or an oxygen mixture air with a vaporized anesthetic； a closed circuit-type or semi-closed circuit-type respiratory circuit including a gas circulation passage configured to circulate the hydrogen-containing anesthesia gas containing the hydrogen gas and the vaporized anesthetic； and a hydrogen concentration measurement circuit configured to measure the hydrogen concentration in the hydrogen-containing anesthesia gas in the gas circulation passage, wherein the hydrogen concentration measurement circuit includes: an anesthetic removing member having a removability of the vaporized anesthetic in the hydrogen-containing anesthesia gas； and a hydrogen concentration measuring instrument provided on the secondary side of the anesthetic removing member.
