PROBLEM TO BE SOLVED: To provide a self-propelled working machine that reduces the reduction of work amount at the time when a work load is high, while sufficiently securing allowance of battery energy required for return traveling to a charging station.SOLUTION: A self-propelled working machine detects the voltage (62, 67) of a secondary battery and each load current (61, 66) of a working motor and a wheel motor by control means, and calculates a load current average value averaged by the hours being spent for mowing work from a total value of a load current. The control means selects any one of determination thresholds (predetermined value V3 or a predetermined value V2) of a battery voltage drop according to the load current average value, performs comparison between the selected threshold and the battery voltage, and stops the mowing work traveling when reaching the threshold and starts the return traveling to a charging station. Here, the threshold (predetermined value V3)) of a high value is selected when a current average value is low, and the threshold (predetermined value V2) of a low value is selected when the current average value is high.SELECTED DRAWING: Figure 5COPYRIGHT: (C)2018,JPO&INPIT【課題】 充電ステーションへの帰還走行に要する電池エネルギーの余裕を十分に確保しながら、作業負荷が高いときの作業量の低下を低減した自走式作業機を提供する。【解決手段】 制御手段によって、二次電池の電圧（６２、６７）の検出と、作業用モータと前記車輪用モータの夫々の負荷電流（６１，６６）の検出を行い、負荷電流の合算値から草刈作業に費やしている時間で平均化した負荷電流平均値の算出を行う。制御手段は、負荷電流平均値に応じて電池電圧低下の判定閾値（所定値Ｖ３、所定値Ｖ２）のいずれかを選択し、選択された閾値と電池電圧との比較を行い、閾値に到達したら草刈作業走行を中断して充電ステーションへの帰還走行を開始する。ここでは、電流平均値が低いときは高い値の閾値（所定値Ｖ３）を選択し、電流平均値が高いときは低い値の閾値（所定値Ｖ２）を選択する。【選択図】図５
