A flow resistor includes a housing, a pipe, and an adjuster. The housing includes a through hole including a first hole portion and a second hole portion. The pipe includes a first extending portion and a second extending portion that extends in a direction different from an extending direction of the first extending portion. The adjuster includes a through hole. The pipe is inserted into the through hole of the housing, the first extending portion is positioned in the first hole portion, and the second extending portion is positioned in the second hole portion. The adjuster is positioned in the second hole portion and is a member movable toward the second extending portion. The through hole of the adjuster couples a space between the adjuster and the pipe with an outside of the flow resistor, in the second hole portion.