An electrical connection device includes a connector unit (2) having first connectors aligned in an arrangement direction, second connectors and a connecting tool (30). The connecting tool (30) detachably holds the second connectors in an alignment corresponding to that of the first connectors. One of the connector unit (2) and the connecting tool (30) includes a guided portion (5), and the other includes a guiding portion (50). The guiding portion (50) includes a receiving portion for receiving the guided portion (5) in a receiving direction, a connection guiding portion for guiding the guided portion (5) to displace the connector unit (2) and the connecting tool (30) in a connector connecting direction as the connector connecting tool (30) is operated with respect to the connector unit (2) in the arrangement direction, and a separation allowing portion for allowing separation of the guided portion (5) from the connection guiding portion.