A plurality of supports and a top plate attached to between upper ends of the supports are provided, and a power storage device and a controller are installed on the both upper and lower sides of the top plate respectively. Meanwhile, a hydraulic pump and a control valve are accommodated in space for hydraulic devices on the lower side of the top plate, and a heat insulating member and heat shield plates are provided as heat shield means for protecting the power storage device and the controller against heat from the exterior including heat of the hydraulic pump and the control valve.