A surgical instrument comprising: a hollow tubular member having a cutting blade disposed on a distal end thereof; a handpiece connected to a proximal end of the hollow tubular member and having a suction passage that connects to the hollow tubular member; a suction pump that is configured to aspirate tissue that is cut by the cutting blade; a pressurization unit provided between the suction passage and the suction pump, the pressurization unit comprising: an outer valve portion having a first port that connects to the suction passage and a second port that connects to the suction pump; a pressurization device connected to the outer valve portion, the pressurization device having a movable part that is configured to generate pressurized fluid when the movable part is moved; an inner valve portion that is slidably provided within the outer valve portion and that is configured to move from a first position to a second position, the inner valve portion including: a first flow passage that extends through the inner valve portion and is configured to connect the first port and the second port of the outer valve portion to each other when the inner valve portion is in the first position; and a second flow passage that is configured to connect the first port of the outer valve portion to the pressurization device when the inner valve portion is in the second position, the second flow passage extending through the inner valve portion and having a first end that opens at a first end of the inner valve portion and a second end that opens at a side surface of the inner valve portion, wherein the pressurization unit is configured such that the pressurized fluid from the pressurization device causes the inner valve portion to move from the first position to the second position, thereby providing positive pressure to the hollow tubular member. a hollow tubular member having a cutting blade disposed on a distal end thereof; a handpiece connected to a proximal end of the hollow tubular member and having a suction passage that connects to the hollow tubular member; a suction pump that is configured to aspirate tissue that is cut by the cutting blade; a pressurization unit provided between the suction passage and the suction pump, the pressurization unit comprising: an outer valve portion having a first port that connects to the suction passage and a second port that connects to the suction pump; a pressurization device connected to the outer valve portion, the pressurization device having a movable part that is configured to generate pressurized fluid when the movable part is moved; an inner valve portion that is slidably provided within the outer valve portion and that is configured to move from a first position to a second position, the inner valve portion including: a first flow passage that extends through the inner valve portion and is configured to connect the first port and the second port of the outer valve portion to each other when the inner valve portion is in the first position; and a second flow passage that is configured to connect the first port of the outer valve portion to the pressurization device when the inner valve portion is in the second position, the second flow passage extending through the inner valve portion and having a first end that opens at a first end of the inner valve portion and a second end that opens at a side surface of the inner valve portion, wherein an outer valve portion having a first port that connects to the suction passage and a second port that connects to the suction pump; a pressurization device connected to the outer valve portion, the pressurization device having a movable part that is configured to generate pressurized fluid when the movable part is moved; an inner valve portion that is slidably provided within the outer valve portion and that is configured to move from a first position to a second position, the inner valve portion including: a first flow passage that extends through the inner valve portion and is configured to connect the first port and the second port of the outer valve portion to each other when the inner valve portion is in the first position; and a second flow passage that is configured to connect the first port of the outer valve portion to the pressurization device when the inner valve portion is in the second position, the second flow passage extending through the inner valve portion and having a first end that opens at a first end of the inner valve portion and a second end that opens at a side surface of the inner valve portion, wherein a first flow passage that extends through the inner valve portion and is configured to connect the first port and the second port of the outer valve portion to each other when the inner valve portion is in the first position; and a second flow passage that is configured to connect the first port of the outer valve portion to the pressurization device when the inner valve portion is in the second position, the second flow passage extending through the inner valve portion and having a first end that opens at a first end of the inner valve portion and a second end that opens at a side surface of the inner valve portion, wherein the pressurization unit is configured such that the pressurized fluid from the pressurization device causes the inner valve portion to move from the first position to the second position, thereby providing positive pressure to the hollow tubular member.