A connection device for a low-voltage power circuit breaker, wherein the circuit breaker comprises: a fixed part, provided with terminals for connection to an electric circuit in which the circuit breaker is inserted, and with disconnection contacts; a movable part, which can be coupled to the fixed part and comprises an auxiliary module which has contact means, and an interruption block which contains at least one fixed contact and a moving contact which can be mutually coupled and are electrically connected to the contact means; its particularity consists of the fact that is comprises a first conducting element which is suitable to be connected to a corresponding disconnection contact and a second conducting element which is suitable to be connected, respectively, to the first conducting element and to the contact means.