A silencer includes: a housing that has a draw-in portion drawing in fluid, and a plurality of sound attenuating portions arranged in a flowing direction of the fluid; a first partition provided with an intermediate communicating portion communicating the most downstream attenuating portion with the adjacent attenuating portion located adjacent to the most downstream attenuating portion; a valve portion disposed in the most downstream attenuating portion, the valve portion being capable of closing the intermediate communicating portion; a valve holding portion holding the valve portion, the valve holding portion being detachably attached to the housing; and a draw-out portion provided in a portion of the most downstream attenuating portion other than the valve holding portion, the draw-out portion drawing out the fluid from the most downstream attenuating portion.