The present invention relates to a clamping unit for an injection molding machine, comprising a displaceable clamping plate (2), a support plate (3) and a drive device acting between the displaceable clamping plate (2) and the support plate (3), which has at least one electric motor (21, 121) and at least one connecting rod (10-13; 110-113), wherein the electric motor (21, 121) directly or indirectly acts on the connecting rod or connecting rods (10-13; 110-113) for opening, closing and/or applying the clamping force. According to the invention, it is proposed to provide in addition to the electric motor (21, 121) at least one separate hydraulic drive (116, 116′, 116″), which is joined by a hinge separately to a connecting rod and acts in parallel to and independently of the electric motor at least at times for opening, closing and/or applying the clamping force.