PURPOSE: To guide an overflowing fuel to a desired position by installing an elastic guide member on a flange connection part, and forming a fuel guide passage in it in a fuel tank comprising an upper and a lower tank members connected to each other at flanges formed at peripheries of them.

CONSTITUTION: A fuel tank 14 disposed roughly at a center part of a subsidiary frame 2b of a steel pipe extended diagonally upward to compose a car body frame of a motor-bicycle is composed by connecting a plate-shaped upper tank member 15 and a lower tank member 16 respectively having flange parts 15a, 16a at peripheries at the flange parts 15a, 16a to each other. In this case, a guide member 17 of rubber having a roughly U-letter shaped plan view is installed on a flange 14 (15a, 16a) of the fuel tank 14. A circumferential wall 17a extended upward is formed on a outer circumferential edge part, and a flange installation groove 17b is formed on an inner circumferential surface in the guide member 17. A hose 18 is connected to an insertion hole 17d formed in a curvature part 17f of the guide member 17 for communication.