The invention relates to a firing safety device for a pyrotechnic device which incorporates a barrier blocking a transmission channel connecting an igniter and a pyrotechnic charge wherein the barrier comprises at least two elements able to move with respect to one another by the action of motor means between a safety position in which they cooperate to block the transmission channel and an armed position in which they free at least partially one part of the transmission channel, each barrier element alone being unable to block the channel.