Abstract: A riding-type lawn mower has a cutter housing with a rear discharge slot defined in a rear wall thereof. The cutter housing accommodates a pair of cutter blades laterally spaced from each other and rotatable in a substantially horizontal plane. The cutter blades are arranged such that the cutter blade on the righthand side as viewed in a forward direction of the lawn mower body is rotatable clockwise as viewed in plan and the cutter blade on the lefthand side as viewed in the forward direction of the lawn mower body is rotatable counterclockwise as viewed in plan. The cutter housing has an upper wall that has a pair of laterally spaced portions raised upwardly and defining respective discharge passages in the cutter housing that lead to the rear discharge slot. Rotative power from a lawn mower engine is transmitted to the cutter blades by a belt-and-pulley mechanism disposed on a low flat portion defined between the raised portions of upper wall.