A pressurized-type writing implement (1, 101) in which: a ballpoint refill (8, 108) is housed in a shaft tube (4, 104), wherein the ballpoint refill (8, 108) includes an ink storage tube (10, 110) filled with a writing implement ink composition, and a ballpoint tip (13, 113) on a front part of the ink storage tube (10, 110); a pressurized chamber (20, 120) and a pressurizing mechanism (7, 107) that applies a pressure to the pressurized chamber (20, 120) are disposed on a back side of the ballpoint refill (8, 108), wherein the pressurized chamber (20, 120) is in communication with a back end of the writing implement ink composition; and a front end of the ballpoint refill (8, 108) is configured to project from a front end opening (3a, 103a) of the shaft tube (4, 104) by pushing a knock body (6, 106) disposed on the back side of the pressurizing mechanism (7, 107) to the front side; a cam member (23, 123) is disposed on the front side of the knock body (6, 106); a pressurizing-force adjusting mechanism (24, 124) is disposed on the back side of the pressurizing mechanism (7, 107), wherein the pressurizing-force adjusting mechanism (24, 124) increases or decreases a volume of the pressurized chamber (20, 120) at least during writing, by rotating the knock body (6, 106); and a first spring body (14, 114) is disposed between an outer step part (8a, 108a) of the ballpoint refill (8, 108) and an inner step part (3b, 103b) of the shaft tube (4, 104), so as to elastically urge the ballpoint refill (8, 108) to the back side with respect to the shaft tube (4, 104); and when the knock body (6, 106) is pushed to the front side or when the ballpoint refill (8, 108) is moved to the back side by a writing pressure upon writing, the pressurizing mechanism (7, 107) is actuated so as to apply a pressure to the back end of the writing implement ink composition; and the pressure applied to the back end of the writing implement ink composition is configured to be adjustable by the pressurizing-force adjusting mechanism (24, 124), characterized in that a slide member (5, 105) that is formed to be movable in a back and forth direction with respect to the shaft tube (4, 104) is disposed outside the knock body (6, 106), the knock body (6, 106) is locked so as to be rotatable and immovable in the back and forth direction with respect to the slide member (5, 105), and the cam member (23, 123) is locked so as to be movable in the back and forth direction and unrotatable with respect to the slide member (5, 105); and the slide member (5, 105), the knock body (6, 106) and the cam member (23, 123) constitute the pressurizing-force adjusting mechanism (24, 124). a ballpoint refill (8, 108) is housed in a shaft tube (4, 104), wherein the ballpoint refill (8, 108) includes an ink storage tube (10, 110) filled with a writing implement ink composition, and a ballpoint tip (13, 113) on a front part of the ink storage tube (10, 110); a pressurized chamber (20, 120) and a pressurizing mechanism (7, 107) that applies a pressure to the pressurized chamber (20, 120) are disposed on a back side of the ballpoint refill (8, 108), wherein the pressurized chamber (20, 120) is in communication with a back end of the writing implement ink composition; and a front end of the ballpoint refill (8, 108) is configured to project from a front end opening (3a, 103a) of the shaft tube (4, 104) by pushing a knock body (6, 106) disposed on the back side of the pressurizing mechanism (7, 107) to the front side; a cam member (23, 123) is disposed on the front side of the knock body (6, 106); a pressurizing-force adjusting mechanism (24, 124) is disposed on the back side of the pressurizing mechanism (7, 107), wherein the pressurizing-force adjusting mechanism (24, 124) increases or decreases a volume of the pressurized chamber (20, 120) at least during writing, by rotating the knock body (6, 106); and a first spring body (14, 114) is disposed between an outer step part (8a, 108a) of the ballpoint refill (8, 108) and an inner step part (3b, 103b) of the shaft tube (4, 104), so as to elastically urge the ballpoint refill (8, 108) to the back side with respect to the shaft tube (4, 104); and when the knock body (6, 106) is pushed to the front side or when the ballpoint refill (8, 108) is moved to the back side by a writing pressure upon writing, the pressurizing mechanism (7, 107) is actuated so as to apply a pressure to the back end of the writing implement ink composition; and the pressure applied to the back end of the writing implement ink composition is configured to be adjustable by the pressurizing-force adjusting mechanism (24, 124), characterized in that a slide member (5, 105) that is formed to be movable in a back and forth direction with respect to the shaft tube (4, 104) is disposed outside the knock body (6, 106), the knock body (6, 106) is locked so as to be rotatable and immovable in the back and forth direction with respect to the slide member (5, 105), and the cam member (23, 123) is locked so as to be movable in the back and forth direction and unrotatable with respect to the slide member (5, 105); and the slide member (5, 105), the knock body (6, 106) and the cam member (23, 123) constitute the pressurizing-force adjusting mechanism (24, 124).