[Problem] To provide a co-infusion device that can appropriately automate some or all of a co-infusion process. [Solution] A co-infusion device (1) is provided with the following: a first robotic arm (21) that holds a medicament container; a second robotic arm (22) that performs the action of inserting the needle of a syringe into an opening in the medicament container held by the first robotic arm (21) and also performs the action of inserting the needle of said syringe into a co-infusion port in an infusion bag; a co-infusion process chamber (104) that contains the robotic arms and the like; and an infusion-bag raising/lowering/tilting unit (113) that holds the infusion bag outside the co-infusion process chamber (104) and positions the co-infusion port of the infusion bag at a co-infusion connecting opening (37) formed in the co-infusion process chamber (104). A waste-containing-chamber door (13) is provided in the front of the co-infusion device (1).