A running board for an all-terrain vehicle includes structure for substantially blocking snow, mud and the like from landing onto the running board during operation, and also for blocking engine heat from excessively warming the feet of a rider. In a running board including a step portion which is positioned on a side of a powertrain unit having an operation pedal in a side portion thereof, a partition is provided between the engine and the step portion, the partition including an insertion opening portion into which the operation pedal is inserted. The partition can be made wider since the operation pedal is inserted into the insertion opening portion blocking snow, mud and the like from coming through a space between the running board and the engine. The partition plate also tends to block engine heat from excessively warming the feet of a rider.