FUEL TANK OF WORKING VEHICLE

A fuel tank (40) includes an upper surface portion (42), a bottom surface portion (44), and a peripheral wall portion (50), and a weir portion (60) vertically arranged at the bottom surface portion (44) and causing a fuel in a predetermined amount to stay in a predetermined position of an inner portion when a vehicle body (10) is inclined. The peripheral wall portion (50) includes a first wall (51) and a second wall (52) which is perpendicular to and continuous with one end side of the first wall (51). The weir portion (60) includes a first barrier (61), a second barrier (62), a third barrier (63) parallel to the first barrier (61), a fourth barrier (64) parallel to the first barrier (61) and arranged between the first barrier (61) and the third barrier (63), and a fifth barrier (65) interconnecting the third barrier (63) and the fourth barrier (64).