An intra-abdominal cavity operation supporting forceps includes, in the vicinity of a grasping portion which includes an openable/closable grasping member provided on a distal end side of a treatment instrument insertion portion, a grasping portion opening/closing operation portion configured to switch the grasping member between an open state and a closed state. In a medical procedure using the intra-abdominal cavity operation supporting forceps, an operating surgeon and an assistant observes an endoscopic image inside a body using an endoscope inserted into a body through a first trocar, the assistant operates the intra-abdominal cavity operation supporting forceps inserted into the body through the second trocar, the operating surgeon operates a treatment instrument inserted into the body through a third trocar, and the operating surgeon operates the grasping portion opening/closing portion of the intra-abdominal cavity operation supporting forceps operated by the assistant with the treatment instrument operated by the operating surgeon himself/herself, depending on a situation of the procedure, while observing the endoscopic image, to cause the grasping member of the intra-abdominal cavity operation supporting forceps to close, thereby causing the grasping portion of the intra-abdominal cavity operation supporting forceps to grasp a tissue.
