A valve apparatus comprising: a body with a supply passage for gas; and a solenoid valve housed in the body, wherein the solenoid valve includes: a tubular sleeve internally having a flow passage leading to the supply passage; an opening and closing portion (32, 37) that opens and closes the flow passage; and a driving portion (31, 33, 34, 35) that drives the opening and closing portion (32, 37) so that the opening and closing portion (32, 37) opens and closes the flow passage, wherein a seal member is disposed between an outer wall of the sleeve and an inner wall of the body, characterized in that a tip of the sleeve on a downstream side of the opening and closing portion (32, 37) is exposed from the body, and the sleeve includes a communication groove formed on an outer peripheral surface of the sleeve in communication with the supply passage and an introduction passage that allows the communication groove and the flow passage in the sleeve to communicate with each other, and the communication groove is formed along the outer peripheral surface of the sleeve so as to extend from a portion of the sleeve at which the communication groove communicates with the supply passage to a position on the opposite side of a central axis (m) of the sleeve. a body with a supply passage for gas; and a solenoid valve housed in the body, wherein the solenoid valve includes: a tubular sleeve internally having a flow passage leading to the supply passage; an opening and closing portion (32, 37) that opens and closes the flow passage; and a driving portion (31, 33, 34, 35) that drives the opening and closing portion (32, 37) so that the opening and closing portion (32, 37) opens and closes the flow passage, wherein a seal member is disposed between an outer wall of the sleeve and an inner wall of the body, characterized in that a tip of the sleeve on a downstream side of the opening and closing portion (32, 37) is exposed from the body, and the sleeve includes a communication groove formed on an outer peripheral surface of the sleeve in communication with the supply passage and an introduction passage that allows the communication groove and the flow passage in the sleeve to communicate with each other, and the communication groove is formed along the outer peripheral surface of the sleeve so as to extend from a portion of the sleeve at which the communication groove communicates with the supply passage to a position on the opposite side of a central axis (m) of the sleeve. a tubular sleeve internally having a flow passage leading to the supply passage; an opening and closing portion (32, 37) that opens and closes the flow passage; and a driving portion (31, 33, 34, 35) that drives the opening and closing portion (32, 37) so that the opening and closing portion (32, 37) opens and closes the flow passage, wherein a seal member is disposed between an outer wall of the sleeve and an inner wall of the body, characterized in that a tip of the sleeve on a downstream side of the opening and closing portion (32, 37) is exposed from the body, and the sleeve includes a communication groove formed on an outer peripheral surface of the sleeve in communication with the supply passage and an introduction passage that allows the communication groove and the flow passage in the sleeve to communicate with each other, and the communication groove is formed along the outer peripheral surface of the sleeve so as to extend from a portion of the sleeve at which the communication groove communicates with the supply passage to a position on the opposite side of a central axis (m) of the sleeve.