An actuation device for ejecting a removable part of a missile includes a pyrotechnic actuator having a pyrotechnic charge configured to generate an overpressure and a piston configured to act on the removable part of the missile, at least one retaining rod, and at least one thermal insulation element configured to thermally insulate at least the pyrotechnic charge. The pyrotechnic actuator is configured to break the retaining rod.