A cap adaptable to the prevention of the application tip body of a liquid container from being dried up by supplying a vaporized solvent thereto, characterized in that it is configured in such a manner that its supply of solvent is difficult to obstruct.When the cap is attached to the liquid container, since the tip of the brush of the liquid container is inserted into the inside space of the inner cap and the tip fitting of the liquid container biases the opening/closing member toward the innermost portion of the cap body against the energizing force of the spring, the transverse hole of the cylindrical portion communicates with the innermost portion of the cap body, which allows the vaporized solvent out of the solvent-impregnation medium to pass through the transverse hole, the longitudinal hole and the solvent passage, and around the flange portion of the inner cap, thus the solvent reaches the brush of the liquid container, as a result, the brush is moistened and prevented from being dried up. Even in the case where the viscous liquid springs out from the brush, the viscous liquid will scatter within the inner cap alone.