An armrest (8, 208) and a chair (100, 200) according to the present invention are provided with: an armrest body (8b, 208b) which is a movable member including a placing surface for supporting a limb of a seated person, and which is supported by a support rod (8a, 208a) from below so as to be movable in a horizontal direction; and a through-space (S, 200S) which is a guide portion indicating the position to be touched by the seated person when moving the armrest body (8b, 208b).