PURPOSE:To enable loading/unloading of a longitudinal container between a lateral container and chassis, by pivoting a frame at the rear section of chassis while pivoting a slidable L-shaped frame rotatably to said frame. CONSTITUTION:A frame 3 is pivoted 2 at the rear end of chassis 1 while a slidable L-shaped frame 4 is pivoted rotatably at the tip of said frame 3. Then L-shaped sliding member 7 is fitted in the guide member 6 and a telescopable cylinder 8 is coupled between said members 6, 7. Furthermore, a launching cylinder 9 is coupled between the chassis 1 and the guide member 6. When unloading a longitudinal container (C) mounted on the chassis 1 while rising vertically, said cylinder 9 is extended to bring said frame 3 and L-shaped frame 4 to vertical position then said cylinder 8 is contracted to ground the longitudinal container (C).