PROBLEM TO BE SOLVED: To improve maneuverability of an airframe by an operation arm in a paddy field work machine. SOLUTION: A non-use posture B1 standing up at the front part of the airframe and a use posture B2 extending from the front part of the airframe to the front side are provided with an operation arm 53 supported by the front part of the airframe so that the posture can be changed. .. A straight-ahead holding linkage mechanism 73 is provided for transmitting a change in posture of the operation arm 53 from the non-use posture B1 to the use posture B2 to the holding portion 68 and holding the steering member 36 at the straight-ahead position of the front wheels by the holding portion 68. .. A diff lock interlocking mechanism 85 is provided, which transmits a change in the posture of the operation arm 53 from the non-use posture B1 to the use posture B2 to the diff lock portion 75, and operates the front wheel diff mechanism 50 in the diff lock state by the diff lock portion 75. [Selection diagram] Fig. 18【課題】水田作業機において、操作アームによる機体の操縦性を向上させる。【解決手段】機体の前部で起立した非使用姿勢Ｂ１及び機体の前部から前側に延出された使用姿勢Ｂ２に、姿勢変更可能に機体の前部に支持された操作アーム５３が備えられる。操作アーム５３の非使用姿勢Ｂ１から使用姿勢Ｂ２への姿勢変更を、保持部６８に伝達して、保持部６８により操向部材３６を前輪の直進位置で保持する直進保持連係機構７３が備えられる。操作アーム５３の非使用姿勢Ｂ１から使用姿勢Ｂ２への姿勢変更を、デフロック部７５に伝達して、デフロック部７５により前輪デフ機構５０をデフロック状態に操作するデフロック連係機構８５が備えられる。【選択図】図１８
