A machine tool comprising: a cover that encloses a processing space in which a workpiece is processed and has a window portion for visual inspection of the processing space from outside; a machining processing unit provided in the processing space; an operation panel for inputting instructions to the machining processing unit, the operation panel being provided outside of the cover; and a cooling system for cooling the machining processing unit, wherein the cooling system includes: a coolant supply unit for supplying a coolant into the processing space; a coolant protection unit that operates to limit adhesion of the coolant to the window portion; and a control unit that switches a state of the coolant protection unit based on a result of detection performed by a sensor for detecting an operator present around the cover, characterized in that the control unit brings the coolant protection unit into a first state when the sensor has detected the operator, and brings the coolant protection unit into a second state when the sensor has not detected the operator, the first state is a state in which the coolant protection unit operates, the second state is a dormant state in which the coolant protection unit does not operate or a state in which the coolant protection unit operates at an output lower than that in the first state, the first state is selected from among a plurality of output states, and the control unit selects one from among the plurality of output states based on a duration of the most recent second state. a cover that encloses a processing space in which a workpiece is processed and has a window portion for visual inspection of the processing space from outside; a machining processing unit provided in the processing space; an operation panel for inputting instructions to the machining processing unit, the operation panel being provided outside of the cover; and a cooling system for cooling the machining processing unit, wherein the cooling system includes: a coolant supply unit for supplying a coolant into the processing space; a coolant protection unit that operates to limit adhesion of the coolant to the window portion; and a control unit that switches a state of the coolant protection unit based on a result of detection performed by a sensor for detecting an operator present around the cover, characterized in that the control unit brings the coolant protection unit into a first state when the sensor has detected the operator, and brings the coolant protection unit into a second state when the sensor has not detected the operator, the first state is a state in which the coolant protection unit operates, the second state is a dormant state in which the coolant protection unit does not operate or a state in which the coolant protection unit operates at an output lower than that in the first state, the first state is selected from among a plurality of output states, and the control unit selects one from among the plurality of output states based on a duration of the most recent second state. a coolant supply unit for supplying a coolant into the processing space; a coolant protection unit that operates to limit adhesion of the coolant to the window portion; and a control unit that switches a state of the coolant protection unit based on a result of detection performed by a sensor for detecting an operator present around the cover, characterized in that the control unit brings the coolant protection unit into a first state when the sensor has detected the operator, and brings the coolant protection unit into a second state when the sensor has not detected the operator, the first state is a state in which the coolant protection unit operates, the second state is a dormant state in which the coolant protection unit does not operate or a state in which the coolant protection unit operates at an output lower than that in the first state, the first state is selected from among a plurality of output states, and the control unit selects one from among the plurality of output states based on a duration of the most recent second state.