PURPOSE: To provide the simple, inexpensive fitting structure of a regulating plate for preventing the water splash of a vehicle from being poured on an engine or the like.

CONSTITUTION: A regulating plate 7 is protrusively provided with a hook 8, and a fitting hole 11 with a fit-in opening 11b and a guide groove 11a is bored in a battery carrier 5. After insert-fitting the hook 8 into the fit-in opening 11b to bring it into contact with the holding part 11c of the guide groove 11a, a battery 6 is disposed in such a way as to cover the fit-in opening 11b, thus fixing the hook 8 to the battery carrier 5.