The invention provides a pressurized pen, which is enabled to enhance the sealing property of a compression chamber at a pressurizing time in the knocking operation of a knock mechanism and to improve the durability. A pressuring pump mechanism includes: a pressure member having a front end opening portion communicating with the inside of a medium containing tube and a compression chamber made extensible and contractible in axial direction; and a push member for coming in axial direction into and out of abutment against a rear end opening portion of the pressure member and for pushing the compression chamber of the pressure member in a gas-tight condition in a compressing direction. The push member is associated with the pushing action of a knock mechanism such that it is enabled to irrotationally move toward the rear end opening portion of the pressure member.