An air cleaner structure that is capable of achieving smooth air-intake capability while separating water contained in air to supply clean air to the engine side. A lower half member of an air-intake duct is, when viewed from above, provided with a central partition and partitions located symmetrically in the vicinity of the central partition, partitions located near both ends, and narrowing passages and widening passages surrounded by the partitions. Air enters from the front of the vehicle body and flows like eddy currents from outlet ports of the widening passages to the outlet ports of the narrowing passages like eddy currents. Thus, coarse particulate and dust contained in the air stay on the outlet port side of the air-intake duct.