To filling air by a tire manual pump tool provided with a clip type pump adapter by integratedly coupling the pump adapter installing part connected to a tire manual pump adapter with a valve installing part connected to a tip end of a valve mounted on a small diameter tire adapted to a infant's bicycle for a prescribed angle.

In the case where air is filled into a small diameter tire using a household tire manual pump formed in such a constitution that a clip type pump adapter D is mounted on a tip end of a hose D', an auxiliary tool A is prepared, which is formed by integrating a pump adapter installing part 2 with a valve installing part 1 for a prescribed connecting angle (90° in an example shown in figure). The auxiliary tool A is installed in such a way that a lower end opening of a bottomed cylindrical body 13 of the valve installing part 1 is fitted to a valve port C1 formed on a tip end of the valve C from an upper part, and a coupling body 14 is screwed around the male screw C2 of the valve port C1. After that, an air blowout port D1 formed on a tip end of the hose D' is connected to the pump adapter installing part 2, its connecting condition is held by holding force of a clip D2, the tire manual pump is operated, and air is filled into a tire B.