To provide an automatic starting device of a carburetor allowing improvement of hot restartability of an engine, reduction of manufacturing cost, and compactification.

A wax holder F has openings at its both ends and a female screw F1 in the upper part. A cover holder J comprises a first cylindrical part J2 in a closed-end cup shape and a second cylindrical part J5 in a closed-end cup shape formed on the outer periphery of the first cylindrical part J2 with a clearance W. The lower end of the first cylindrical part J2 is provided with a male screw J4, and the first cylindrical part J2 is provided with a heater 13 connected to terminals T1 and T2, a collar K, a temperature-sensitive driving member C, or the like. An annular space part R in a substantially closed shape is formed along a longitudinal direction X-X of the temperature-sensitive driving member C between an upper cylindrical part F4 of the wax holder F and the second cylindrical part J5 of the cover holder J.