To reduce redundancy in control by providing an auxiliary fuel supply control means relaying on operation capacity and operation function of a main fuel supply control means, and make the auxiliary fuel supply control means receive capacity improving effect thereof by improving operation capacity and operation function of the main fuel supply control means.

In this fuel control device for a bi-fuel vehicle, the fuel supply control device is provided with the auxiliary fuel supply control means performing operation relating to another kind of fuel different form one kind of fuel together with the main fuel supply control means performing operation relating to one kind of fuel out of two or more kinds of fuel supplied to an internal combustion engine. The main fuel supply control means performs operation relating to one kind of fuel and has function for stopping supply of one kind of fuel when another kind of fuel is supplied to the internal combustion engine. The auxiliary fuel supply control means performs operation relating to another kind of fuel by using operation result relating to one kind of fuel by the main fuel supply control means and perform supply of another kind of fuel.