The present invention provides the power portion structure of a combine harvester, which can easily perform a maintenance and inspection work of a hydraulic type continuously variable transmission device. The power portion structure of a combine harvester of the present invention includes: the fan (31) disposed between the engine (E) and the heat radiator (30)； the hydraulic continuously variable transmission device (10) driving the fan (31) in forward or reverse direction； and the electric chamber (26) arranged on the upper side of engine chamber (6) and receiving electric parts. Therefore, the bottom wall (28) of the electric chamber (26) is recessed toward the upper side, and the upper portion of the hydraulic type continuously variable transmission device (10) is arranged at the lower surface side of the recessed portion.本發明提供一種聯合收穫機之動力部構造，其能夠容易地進行油壓式無段變速裝置之保養、檢查作業。 本發明之聯合收穫機之動力部構造係於引擎（E）及散熱器（30）之間設置風扇（31），且設置將風扇（31）向正轉方向及反轉方向驅動之油壓式無段變速裝置（10），於引擎室（6）之上側設置內裝電氣零件之電氣室（26），使電氣室（26）之底壁（28）朝向上側凹陷，將油壓式無段變速裝置（10）之上部配置於該凹陷部分之下表面側。
