Occupant's leg protection system

The object is to provide an occupant's leg protection system in which the direction of the deployment of an airbag includes the direction opposite to the direction of the forward movement of the legs and thus has an excellent characteristic of preventing the legs from moving forward and which is capable of restraining the ankles or the insteps early. An airbag (14) includes a lower chamber (14A) that deploys forward of the insteps to the ankles, an upper chamber (14B) that deploys upward than that, and a duct (14C) that communicates the lower chamber (14A) and the upper chamber (14B) with each other. An inflator (16) is arranged in the lower chamber (14A). The lower chamber (14A) first deploys forward of the toes to the ankles of the occupant's legs and the airbag (14) then deploys upward by the gas from the inflator (16). Since the direction of the deployment of the airbag (14) is opposite to the direction of the forward movement of the legs, a force of preventing the forward movement is applied to the legs from the inflating airbag (14).