A fuel supply device for an internal combustion engine having at least one cylinder that is formed in a cylinder block, a fuel injection valve and a fuel passage that supplies fuel to the fuel injection valve, includes a portion of the fuel passage that is formed as a delivery pipe that is embedded in a cylinder head and is joined to an upper portion of the cylinder block. The fuel injection valve is positioned so that it intersects the delivery pipe and receives the supply of fuel from the side at a portion that intersects with the delivery pipe, and a sealing member is positioned at the joint portion between the delivery pipe and the fuel injection valve.