<p>(Problem) To prevent an infusion solution from foaming or directly contacting a medicament in a vial when said infusion solution is injected into a medicament container in a co-infusion device. (Solution) The following are provided: a first movement unit (41) that holds the cylindrical part (11a) of a syringe (11) and moves said cylindrical part (11a) in the direction in which the piston in said syringe (11) moves; a second movement unit (42) that holds said piston (11b) and moves said piston (11b) in the direction in which said piston moves; a third movement unit (43) that moves a container-holding part (436), which holds a vial (10), in the direction in which the aforementioned piston moves; a support part (44) that supports the abovementioned movement units (41, 42, and 43); a rotational drive unit (45) that rotates said support part (44) to rotate the direction in which the piston moves; and an infusion-bag holding part (5) that holds an infusion bag (12) such that a co-infusion port is opposite the needle of the abovementioned syringe (11) which has been pointed in a prescribed direction by the rotation of the aforementioned support part (44).</p>
