SEALING STRUCTURE IN DIRECT ACTING TYPE AUTO-BY STARTER

To prevent the entry of ambient air and liquid such as rainwater into a direct acting type auto-by starter and thereby prevent the formation of rust in the auto-by starter, by adjusting pressure fluctuations in the auto-by starter caused by the operation of a starting valve for opening and closing a starting intake passage. A starting valve 2 is lifted by upwardly operating a manual lever 7, thereby opening a starting intake passage 1c to start an internal combustion engine. A pressure in a sliding space 2f for the starting valve 2 is increased by the lift of the starting valve 2, so that t he gas in the sliding space 2f flows out of the sliding space 2f. The flow of the g as is absorbed by an increase in volume inside a bellows boot 5 mounted on an upper portion 2b of the starting valve 2. When the starting valve 2 is lowered by the operation of a spring member 6, the pressure in the sliding space 2f is reduced to allow the gas flow from the bellows boot 5 into the sliding space 2f. This gas flow is absorbed by a decrease in volume inside the bellows boot 5, thereby preventing the entry of ambient air and water into the auto-by starter 10.