A key switch including: a support base; a key which is manually operable for being moved, with respect to the support base, between at least a first operating position and a second operating position spaced apart from each other, in order to establish or interrupt at least one electric connection; a leaf spring member operatively interposed between the support base and the key; wherein the first operating position is a stable operating position of the key in which the leaf spring member is deformed between the key and the support base so as to take a first curvilinear configuration.