PROBLEM TO BE SOLVED: To provide an agricultural work machine mounted on a motor tractor for agricultural work that has improved the reliability of a mechanism to extend an extended operation part.SOLUTION: An agricultural work machine 2 mounted on a motor tractor 1 for agricultural work includes: a working part 5 for performing agricultural work an extended work part 6 that can extend the work width of the working part 5 a hydraulic cylinder 24 for operating the extended work part 6 in an extended state or in a non-extended state hydraulic operation means 21 for operating the hydraulic cylinder 24 a valve 23 disposed in an oil passage to the hydraulic cylinder 24 a control part 16 that can control the valve 23 and an operation part 13 that can remotely transmit a signal to the control part 16. Upon receipt of an operation start signal for starting the operation from the operation part 13, the control part 16 turns the valve 23 ON, and allows the hydraulic cylinder 23 to be operated by the hydraulic operation means 21.
