An activation button (20) for electric tools, in particular for welding torches and/or plasma arc torches that can be used for cutting materials, comprising at least one flexible foil (21), suitably shaped, arranged between two portions (13, 15) of the button (20), which are pivoted together at one end (11) to allow the actuation of the electric tool only in the presence of a manual command given by the operator; the structure of the button (20) is thus extremely reliable in terms of electrical continuity, at the same time ensuring extreme ease of construction and assembly, as well as an overall reduction in production costs, with respect to known solutions.