A ride-on mower can easily lift mower deck up and down so that it remains horizontal. The ride-on mower has driving motors, mower blades spinning for mowing grass, mowing motors for the mower blades, batteries for the driving motors and the mowing motors, a mower deck for covering the mower blades from the above and sides and for setting the mowing motors on, and a mower deck lifting device for lifting up and down the mower deck. The mower deck lifting device has a booster for assisting the mower deck lifting device in lifting the mower deck up and down, and the mower deck lifting device is set at the center on the mower deck.
