An anchoring structure for an annular member includes a housing including a first casing and a second casing, and the annular member. The annular member is partially interposed between the first casing and the second casing. The annular member includes an external member that protrudes to an outside of the housing, and an internal member connected to the external member and located on an inside of the housing. The first casing includes a first engagement portion into which a first end of the internal member is inserted, the first engagement portion limiting the first end from moving in a direction away from the first casing. The first casing includes a second engagement portion limiting a second end of the internal member from moving in the direction away from the first casing while the first end of the internal member is engaged with the first engagement portion.