A fuel tank valve device includes a housing in which a partition wall defines a lower valve chamber and an upper ventilation chamber, and a first opening and a second opening are provided to establish a communication between the lower valve chamber and the upper ventilation chamber, a first float valve that is accommodated in a first valve chamber of the lower valve chamber so as to rise and fall and that closes the first opening when a fuel level in a fuel tank nearly reaches a set full fuel level, and a second float valve that is accommodated in a second valve chamber of the lower valve chamber so as to rise and fall and that closes the second opening when the fuel level in the fuel tank rises abnormally.

A valve device for a fuel tank has a housing having a valve chamber which is provided below a partition wall and a ventilation chamber which is provided above the partition wall; a recess having a first opening formed in the bottom section thereof and defining a part of the ventilation chamber; and a fuel vapor discharge opening formed in the inner periphery of the recess. The partition wall has a shelf-like wall section extending from the peripheral edge of a second opening and reaching the inner periphery of the recess. The shelf-like wall section has formed therein a first groove section extending from the second opening side and connecting to the recess. A ceiling wall is disposed above the shelf-like wall section with a gap therebetween.