A medical treatment tool used with a control device, the control device being configured to control a supply of energy to the medical treatment tool, and the control device being capable of functioning in a plurality of operation modes, the medical treatment tool comprising: a housing which includes a housing body extending along a longitudinal axis, and which has a base and a head; an end effector which is placed nearer to a head side than the housing, and which treats an object to be treated; an operation member (31A, 31B) which is placed at a portion near the head of the housing, the operation member (31A, 31B) being configured to be switched between an ON state and an OFF state based on an operation input with the operation member (31A, 31B); and a selection member (41; 41A; 41B; 41C) which is placed on the housing the selection member (41; 41A; 41B; 41C) being configured to be switched between an ON state and an OFF state based on an operation input with the selection member (41; 41A; 41B; 41C), characterized in that the control device is configured to function in a first operation mode based on a switching of the operation member (31A, 31B) from the OFF state to the ON state after the control device detects the OFF state of the selection member (41; 41A; 41B; 41C), the first operation mode being one of the plurality of operation modes, and the control device is configured to function in a second operation mode based on the switching of the operation member (31A, 31B) from the OFF state to the ON state after the control device detects the ON state of the selection member (41; 41A; 41B; 41C), the second operation mode being another one of the plurality of operation modes and being different from the first operation mode. a housing which includes a housing body extending along a longitudinal axis, and which has a base and a head; an end effector which is placed nearer to a head side than the housing, and which treats an object to be treated; an operation member (31A, 31B) which is placed at a portion near the head of the housing, the operation member (31A, 31B) being configured to be switched between an ON state and an OFF state based on an operation input with the operation member (31A, 31B); and a selection member (41; 41A; 41B; 41C) which is placed on the housing the selection member (41; 41A; 41B; 41C) being configured to be switched between an ON state and an OFF state based on an operation input with the selection member (41; 41A; 41B; 41C), characterized in that the control device is configured to function in a first operation mode based on a switching of the operation member (31A, 31B) from the OFF state to the ON state after the control device detects the OFF state of the selection member (41; 41A; 41B; 41C), the first operation mode being one of the plurality of operation modes, and the control device is configured to function in a second operation mode based on the switching of the operation member (31A, 31B) from the OFF state to the ON state after the control device detects the ON state of the selection member (41; 41A; 41B; 41C), the second operation mode being another one of the plurality of operation modes and being different from the first operation mode.