A work machine comprising: an operator seat; a work device having a hydraulic actuator; a support bracket; an operation box supported by the support bracket and pivotally supported by a first lateral shaft disposed on the support bracket, the operation box being rotatable about the first lateral shaft and having an operation lever; an unload lever swingably supported by the operation box, the unload lever being configured to be swung to select whether or not to supply an operation fluid to the hydraulic actuator; a cam body pivotally supported by a second lateral shaft disposed on the operation box and being rotatable about the second lateral shaft, the cam body having a cam groove, a first guide pin disposed on the support bracket; characterized in that the support bracket is disposed on a side of the operator seat and has a first guide groove; a first latch portion is disposed on the first guide groove, a second latch portion is disposed on the first guide groove, the first guide pin moves to positions in the cam groove in accordance with swinging of the unload lever, the first guide pin being positioned on one side of the cam groove when the unload lever is positioned on a pushed-down position and being positioned on the other side of the cam groove when the unload lever is positioned on a pulled-up position, the unload lever includes a second guide pin which moves to positions in the first guide groove in accordance with swinging of the unload lever, the second guide pin being positioned on one side of the first guide groove when the unload lever is positioned on the pushed-down position and being positioned on the other side of the first guide groove when the unload lever is positioned on the pulled-up position, and the first guide groove includes the first latch portion to latch the second guide pin at one end of the first guide groove, and the second latch portion to latch the second guide pin at the other end of the first guide groove. an operator seat; a work device having a hydraulic actuator; a support bracket; an operation box supported by the support bracket and pivotally supported by a first lateral shaft disposed on the support bracket, the operation box being rotatable about the first lateral shaft and having an operation lever; an unload lever swingably supported by the operation box, the unload lever being configured to be swung to select whether or not to supply an operation fluid to the hydraulic actuator; a cam body pivotally supported by a second lateral shaft disposed on the operation box and being rotatable about the second lateral shaft, the cam body having a cam groove, a first guide pin disposed on the support bracket; the support bracket is disposed on a side of the operator seat and has a first guide groove; a first latch portion is disposed on the first guide groove, a second latch portion is disposed on the first guide groove, the first guide pin moves to positions in the cam groove in accordance with swinging of the unload lever, the first guide pin being positioned on one side of the cam groove when the unload lever is positioned on a pushed-down position and being positioned on the other side of the cam groove when the unload lever is positioned on a pulled-up position, the unload lever includes a second guide pin which moves to positions in the first guide groove in accordance with swinging of the unload lever, the second guide pin being positioned on one side of the first guide groove when the unload lever is positioned on the pushed-down position and being positioned on the other side of the first guide groove when the unload lever is positioned on the pulled-up position, and the first guide groove includes the first latch portion to latch the second guide pin at one end of the first guide groove, and the second latch portion to latch the second guide pin at the other end of the first guide groove.