A robot mower includes a left cutter blade unit rotatably about a left vertical shaft to generate a left rotation locus, a right cutter blade unit rotatably about a right vertical shaft to generate a right rotation locus and a center cutter blade unit rotatably about a center vertical shaft to generate a center rotation locus. The left cutter blade unit and the right cutter blade unit are disposed forwardly of the rear wheel unit and spaced apart from each other in a vehicle body transverse direction. A portion of the left rotation locus protrudes more on a lateral outer side than the vehicle body and the left rear wheel and a portion of the right rotation locus protrudes more on a lateral outer side than the vehicle body and the right rear wheel. The center cutter blade unit is disposed between the left rear wheel and the right rear wheel in such a manner as to cover an uncut area formed due to presence of a gap between the left cutter blade unit and the right cutter blade unit.
