PROBLEM TO BE SOLVED: To provide a medical treatment instrument and a medical treatment device which have simple device structures and can be used by switching functions of a laser knife and an electric knife.SOLUTION: A medical treatment instrument inserted into a body lumen is composed of: a hollow laser probe 40 for guiding carbon dioxide laser L which can dissect an affected part P to be treated of a patient M contactlessly and a blade electrode 53 which is conducted via a counter electrode in contact with the patient M and functions at an emission port 40a of the laser probe 40. The blade electrode 53 is separated from the end emission port 40a irradiating the carbon dioxide laser L in the laser probe 40 at a prescribed interval and is placed on an irradiation path of the carbon dioxide laser L, and reflection irregularities 54 for diffusing reflected laser light R of the irradiated carbon dioxide laser L reflected by the blade electrode 53 are formed on the surface of an irradiation surface 53a that is irradiated with the carbon dioxide laser L in the blade electrode 53.
