An engine-driven work machine is provided in which elastic support members (11, 11) are disposed between a lower part of a work unit (U) having an engine (3) and a frame (2) having the work unit (U) mounted thereon, the elastic support members (11, 11) being disposed beneath a crankshaft (17) of the engine on either side of a vertical plane (V) passing through the axis of the crankshaft (17), and restricting means (122) is provided between the work unit (U) and the frame (2), the restricting means (122) restricting the amplitude of swing of the work unit (U) around the crankshaft (17) to within a predetermined angle, and the restricting means (122) being disposed between upper parts of the work unit (U) and the frame (2). Even when the work unit receives a large external force in the lateral direction, swing of the work unit can thereby be restricted to within the predetermined angle.