PURPOSE: To prevent any damage of apparatus or slippage of wheels by providing a convex part which hinders the shift rod from shifting to the low-speed position when the transfer is taking 2-wheel drive mode at an extentional position of the shift rod on the shift fork.

CONSTITUTION: A convex 70a is provided at an extentional position of the shift rod 44 on the shift fork 70. When actuating the shift rod 44 into the low-speed position shown by the 2-dotted chain line by operating the operation lever while the transfer is taking the 2-wheel drive mode, the end face 44e of the shift rod 44 comes into contact against the convex 70a of the fork 70, which hinders the shift rod 44 from moving and consequently the operation lever from shifting into the low-speed drive position. Accordingly, selection of low-speed 2-wheel drive mode by mistake will be eliminated, that prevents the transfer and propeller shaft way from damage as well as the wheels from slippage due to excessive engine braking.