To investigate the effects of paper sludge, by-products of paper manufactory, on the chemical properties of paddy soil and growth of paddy rice, paper sludges were applied to the pots at the rates of 300, 600, 900 and 1,200㎏/l0a which were either pread-justed C/N ratio to 30 : 1 or not adjusted. The effects were compared with those of control. Seasonal variations of various forms of soil organic nitrogen, the mineralization of organic nitrogen and the contents of soil minerals were analyzed. The results were summarized as follows: 1) The contents of soil organic nitrogen, especially amino sugar-N and amino acid-N, organic matter, CEC and available $SiO_2$ were increased by application of paper sludge compared with that of control. 2) The mineralizations of organic nitrogen after 6 weeks of incubation at $30^{circ}C$ were 12. 2, 12.6, 15.1, 9.7 and $15.2^{circ}C$ in the control, 300㎏/l0a sludge treatment, 300㎏/l0a sludge treatment(C/N ratio adjusted), 600㎏/l0a sludge treatment and 600㎏/l0a sludge treatment(C/N ratio adjusted), respectively. 3) Cu and Pb contents in the soil were in the range of $0{sim}0.2100$ and $0{sim}0.0013$ ppm, respectively. Cr and Cu in the soil were not detected at all. There were no differences in the contents of all the heavy metals among all the treatments in the soil.