To solve a problem that a sub-transmission device of a gear switching type in which switching operation to different transmission stages can be quickly and preferably performed by an actuator is desired.SOLUTION: A harvester includes: a manual type sub-transmission operation tool 73 that instructs switching of a transmission state of a sub-transmission device； an actuator CY3 that operates an operation member for performing gear shift in the sub-transmission device； a travelling state determination means 72 that determines whether it is a low speed travelling state in which the vehicle speed is slower than a set vehicle speed set in advance； and a control means 79 that control actuation of the actuator CY3. When the travelling state determination means 72 determines that it is the low speed travelling state, the control means 79 actuates the actuator CY3 so as to switch the transmission state to the state corresponding to the instruction of the sub-transmission operation tool 73, and when the travelling state determination means 72 does not determine that it is the low speed determination state, the control means 79 restricts actuation of the actuator CY3 irrespective of the instruction of the sub-transmission operation tool 73.SELECTED DRAWING: Figure 10【課題】ギア切替式の副変速装置において、異なる変速段への切り換え操作をアクチュエータにて迅速に且つ良好に行えるようにすることが望まれていた。【解決手段】副変速装置の変速状態の切り換えを指令する手動式の副変速操作具７３と、副変速装置におけるギアシフトを行う操作部材を操作するアクチュエータＣＹ３と、車速が予め設定された設定車速よりも低速である低速走行状態であるか否かを判定する走行状態判定手段７２と、アクチュエータＣＹ３の作動を制御する制御手段７９とが備えられ、制御手段７９は、走行状態判定手段７２にて低速走行状態が判定されるときは、副変速操作具７３の指令に対応する変速状態に切り換えるようにアクチュエータＣＹ３を作動させ、且つ、走行状態判定手段７２にて低速走行状態が判定されないときは、副変速操作具７３の指令にかかわらずアクチュエータＣＹ３の作動を禁止する。【選択図】図１０
