A writing instrument is provided with a barrel including a bottom opening; a partition disposed in the barrel to divide the barrel into an upper ink reservoir filled with ink and a lower storage filled with an absorbent material; a writing member partially disposed in the absorbent material and extending out of the bottom opening; and a conveying line disposed through the partition. The conveying line includes a venting channel and an ink conveying channel. Each of the venting channel and the ink conveying channel communicate with both the ink and the absorbent material. A smooth writing can be carried out.