This study was conducted to reduce degradation of marketability by the rot and discolor of onion bulbs under room temperature from 1977 to 1998. Allium cepa cv. Changnyungdeago, late strain, was used for the test at the storage condition of non-shading, 55% and 95% shadings. The results obtained are as follows: The mean temperature was maintained lowly 1.0∼2.9$^{C}$ in 55% and 2.0∼3.8$^{C}$ in 95% shadings in contrast to nun-shading, but the relative humidity was a tittle higher in high shading than other shading condition. The illumination and color density maintained lowly in high shading. After 21 days of storage, the rate of discolored onion bulbs was significantly higher in non-shading(90.0%) than 55%(35.7%) and 95%(13.3%) shadings. The rotting rate by the end of August was a little decreased at 55%(25.4%) and 95% shadings(26.5%) in contrast to non-shading(28.9%), and total weight loss was maintained lowly in high shading.