The present invention is directed to providing a transfer tube assembly mounted on a saddle type fuel tank. The assembly of the present invention includes: a main fuel pump allowing a fuel pump system to deliver fuel to the engine; a sender delivering residual fuel to the main fuel pump; a wire harness connecting the main module and the sender and configured to inform of a fuel amount in the sender; and a transfer tube for transferring the residual fuel in the sender to the main fuel pump. The wire harness and the transfer tube are integrally coupled and configured so that a function of the wire harness can be performed simultaneously with a function of the transfer tube.