A medical instrument effectively suppresses a situation in which the edge of a blade springs immediately after completion of incision, excision, or the like. The medical instrument (1) includes manipulation members (14) that are held by a user, elastic members (11) that are respectively secured on one end of the manipulation members, and intersect each other at one end thereof, and opening-closing members (15) that are respectively secured on the other end of the manipulation members (14), and intersect each other at a pivot (13), functional parts (15a) for implementing a gripping operation, a holding operation, a cutting operation, or the like being respectively provided at one end of the opening-closing members (15), the functional parts (15a) being opened and closed by adjusting a pressing force applied to the manipulation members (14), the opening-closing members (15), the manipulation members (14), and the elastic members (11) being configured so that the pressing force applied to the manipulation members (14) and an opening-closing amount of the functional parts (15a) have a linear proportional relationship during a period in which the functional parts (15a) are operated.