In this case the decompression process may be omitted as ink can be filled in the porous member 2 a owing to the capillary action generated by the porous member 2 a itself. [0044] Such hydrophilic treatment can be realized by impregnating porous member 2 a with water, polyhydric alcohol such as ethylene glycol or glycerin or its aqueous solution, surfactant or its aqueous solution, or their compos