A grass mower is provided with a plurality of rotating shafts passing through a ceiling wall of a mower deck and extending upward, disposed in a side-by-side state; cutting blades respectively linked to the rotating shafts in an internal space of the mower deck; an electric motor mounted at a location to the lateral outside relative to a rotation path of the cutting blades within the mower deck, and having an output shaft extending upward; and a power transmission mechanism positioned above the ceiling wall of the mower deck, and configured to transmit power from the output shaft to the rotating shafts of the cutting blades.
