A connection terminal clamping device (2) clamping a conductor wire (3) to a connection conductor bar (4) comprises a part forming a conductor housing (5) provided with at least one upwardly oriented opening for receiving at least one connectable conductor wire (3) and the connection conductor bar (4), a clamping spring (13) which maintains the conductor wire (3) introduced into a housing-formingpart in position against the conductor bar (4) by means of an elastic force and which comprises a first connecting arm (15) formed by the extension of a wall defining said housing-forming part (5) and connected by an elbow (16) to a second clamping arm (17) provided with a free clamping end (18).