A lubricating mechanism includes: a rotational shaft; a casing housing a rear-end of the rotational shaft; a bearing between the rotational shaft and the casing; and an oil seal between the casing and one of the rotational shaft and a member rotatable with the rotational shaft in a space behind the bearing. The rotational shaft includes: a first oil passage extending from a front of the bearing towards the bearing; a second oil passage extending radially under the bearing, one side thereof communicating with the first oil passage and the other side thereof opening at a periphery of the rotational shaft; and a third oil passage extending between the periphery of the rotational shaft and an inner periphery of the bearing, one side thereof communicating with the other side of the second oil passage and the other side thereof communicating with the space.