Provided is a backpack working machine with excellent operability and durability, the machine having a configuration in which a blower is mounted on a backpack frame with a vibration isolation device interposed therebetween, and a drive source and a fuel tank are attached to the blower. The machine includes a backpack frame with a backrest portion, the backrest portion being adapted to abut an operators back, a blower mounted on the backrest portion with a vibration isolation device interposed therebetween, an engine attached to the blower for driving the blower, and a fuel tank that stores a fuel to be supplied to the engine. The fuel tank is attached to the blower such that the fuel tank is located at at least one of a position below the engine or on a lateral side of the engine.
