A grass cutter comprising: a mower deck configured to house a rotating blade for mowing grass therein; a blower configured to convey the grass mowed by the rotating blade to a grass collection vessel; a blower PTO transmission shaft configured to be connected with the blower, a drive force low-speed transmitting passage through which a drive force from a drive source is transmitted at low speed; a drive force high-speed transmitting passage through which the drive force from the drive source is transmitted at high speed; and a mower PTO transmission shaft configured to transmit the drive force to the rotating blade in the mower deck; characterized in that the grass cutter further includes: a blower PTO hydraulic clutch configured to connect the blower PTO transmission shaft with the drive force low-speed transmitting passage, connect the blower PTO transmission shaft with the drive force high-speed transmitting passage, and shift the blower PTO transmission shaft in a neutral state in which the blower PTO transmission shaft is not connected with the drive force low-speed transmitting passage and the drive force high-speed transmitting passage; and a mower PTO hydraulic clutch configured to switch transmission and interruption of the drive force to the mower PTO transmission shaft, wherein the grass cutter further includes: a mode selection unit configured to select a grass collection mode, in which the blower PTO transmission shaft and the mower PTO transmission shaft are driven, and a work mode, in which the mower PTO transmission shaft is driven, by operation; and a high-speed/low-speed selection unit configured to select a low-speed drive, in which the blower is connected with the drive force low-speed transmitting passage, and a high-speed drive, in which the blower is connected with the drive force high-speed transmitting passage, when the blower is driven in the grass collection mode. a mower deck configured to house a rotating blade for mowing grass therein; a blower configured to convey the grass mowed by the rotating blade to a grass collection vessel; a blower PTO transmission shaft configured to be connected with the blower, a drive force low-speed transmitting passage through which a drive force from a drive source is transmitted at low speed; a drive force high-speed transmitting passage through which the drive force from the drive source is transmitted at high speed; and a mower PTO transmission shaft configured to transmit the drive force to the rotating blade in the mower deck; characterized in that the grass cutter further includes: a blower PTO hydraulic clutch configured to connect the blower PTO transmission shaft with the drive force low-speed transmitting passage, connect the blower PTO transmission shaft with the drive force high-speed transmitting passage, and shift the blower PTO transmission shaft in a neutral state in which the blower PTO transmission shaft is not connected with the drive force low-speed transmitting passage and the drive force high-speed transmitting passage; and a mower PTO hydraulic clutch configured to switch transmission and interruption of the drive force to the mower PTO transmission shaft, wherein a blower PTO hydraulic clutch configured to connect the blower PTO transmission shaft with the drive force low-speed transmitting passage, connect the blower PTO transmission shaft with the drive force high-speed transmitting passage, and shift the blower PTO transmission shaft in a neutral state in which the blower PTO transmission shaft is not connected with the drive force low-speed transmitting passage and the drive force high-speed transmitting passage; and a mower PTO hydraulic clutch configured to switch transmission and interruption of the drive force to the mower PTO transmission shaft, wherein the grass cutter further includes: a mode selection unit configured to select a grass collection mode, in which the blower PTO transmission shaft and the mower PTO transmission shaft are driven, and a work mode, in which the mower PTO transmission shaft is driven, by operation; and a high-speed/low-speed selection unit configured to select a low-speed drive, in which the blower is connected with the drive force low-speed transmitting passage, and a high-speed drive, in which the blower is connected with the drive force high-speed transmitting passage, when the blower is driven in the grass collection mode. a mode selection unit configured to select a grass collection mode, in which the blower PTO transmission shaft and the mower PTO transmission shaft are driven, and a work mode, in which the mower PTO transmission shaft is driven, by operation; and a high-speed/low-speed selection unit configured to select a low-speed drive, in which the blower is connected with the drive force low-speed transmitting passage, and a high-speed drive, in which the blower is connected with the drive force high-speed transmitting passage, when the blower is driven in the grass collection mode.