respect to the extremity end after feeding the compressed air into the liquid tank to pressurize an inside part of the liquid tank during a loading process of the cap in respect to the extremity end enable its machining and assembling to be substantially simplified as compared with that of the prior art writing tool and further enable its manufacturing cost to be reduced the valve opening operation for retracting the rotary member projected out of the extremity end of the tip inwardly toward the tip so as to feed the compressed air into the liquid tank is performed in such a manner that the rotary member is abutted against the inner bottom part of the cap so that the valve opening operation can be maintained positively and stably for a long period of time without being damaged in a short period of time as found in the prior art writing tool fig1 to 13b illustrate a fifth embodiment of the writing tool of the present invention wherein a cylindrical resilient member 19 is loaded at an outer periphery of the extremity end 3 a cap 21 is pushed and loaded up to a cap loading base end 3 1 circumferential step in respect to the extremity end 3 with a cap returning resilient part 20 resilient circumferential ring arranged at an outer periphery of the cylindrical part 19 1 of the resilient member 19 to be described later thereafter the pushing operation is released to cause the cap 21 to be automatically pushed back to the normal loading position of the extremity end 3 then the.