A riding mower including two mower blades that rotate to mow grass and generate air flows, the two mower blades including a left mower blade and a right mower blade, a mower deck, two motors that rotate the respective mower blades and a controller is provided. The left and right mower blades being provided adjacent to each other and one of the left and right mower blades being disposed obliquely in front of the other mower blade. The riding mower generates a combined air flow and discharges mowed grass to the outside of the mower deck together with the combined air flow. The controller controls such that a difference between the rotational speeds of the left and right mower blades is changed at a predetermined period and the mowed grass is discharged to the rear of the mower deck uniformly in a lateral direction of the mower deck.