To provide a portable working machine capable of not only substantially reducing the size but also sufficiently imparting a miniaturized feeling to look at, by restraining the size of a top handle.

A chain saw 1 being the portable working machine has a main body 11 storing an engine 15, the top handle 12 arranged on the upper side of the main body 11, a carburetor 36 stored in the top handle 12 and generating an air-fuel mixture to the engine 15, an air cleaner 25 arranged on the side of the main body 11, and a communicating passage 37 for intake air for communicating this air cleaner 25 with an intake passage of the carburetor 36.

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