Abstract: A vent apparatus of a fuel tank comprising a housing having a through-hole at the bottom communicating with a fuel tank; a valve body mounted on the housing, having a flange, vent slots and a partition wall; a lower cover mounted under the valve body, having a through-hole communicating with the through-hole of the housing and the lower space of the valve body; a ball for opening and closing the through-hole of the partition wall of the valve body; a pushing weight mounted on the upper compartment of the valve body, having a protrusion formed on its bottom to prevent adhesion of the ball to the partition wall of the valve body; and an upper cover positioned on the top of the housing, having a plurality of outlets around its periphery.