A seal structure for a switch mechanism includes a switch disposed in a housing, an operating member protruding forward from the housing through an opening formed in the housing and configured to turn on or off the switch, a rubber cover attached to the operating member from a front-side of the operating member and having a rear end engageable with the opening, and a fixing cover fixed to the operating member from outside the rubber cover so as to integrate the rubber cover with the operating member. In this seal structure, the rubber cover seals gap between the opening and the operating member.