A medical device 1 includes: a medical instrument 4 introduced into a body cavity and having a contact portion 42 that is fixed in contact with a wall within a body, and a wire 45 an extracorporeal device 3 installed on a body surface and having a hole portion through which the wire can be inserted and removed, fixing mechanisms 25 and 26 for fixing the wire inserted through the hole portion, and a housing 21 that is fixed in contact with the body surface and a pressure adjusting portion 62 provided in one of the medical instrument and the extracorporeal device for maintaining a predetermined tensile force or more that is applied to the wire when the wire is fixed by the fixing mechanism with a body wall being sandwiched between the contact portion and the housing.
