A security device for an electronic payment terminal having at least one printed circuit. The security device includes at least one deformable security element designed to be inserted in a housing of the printed circuit. The printed circuit has at least one security circuit including at least one conducting track internal to the printed circuit and interrupted at the housing. Furthermore, the at least one deformable element has at least one conducting surface configured to close the at least one internal conducting track when the deformable element is deformed in the housing.