This study was to investigate the effect of ultraviolet rays, soaking, boiling and baking to ergocalciferol ($Vit.D_2$) and riboflavin($Vit.B_2$) contents of mushrooms, Lentinus edodes, Pleurotus ostreatus and Agaricus bisporus. The results were as follow: 1. Mushrooms were exposed to ultraviolet rays Lentinus edodes : $10J/cm^2$, Pleurotus ostratus : $2J/cm^2$ and Agaricus bisporus : $2J/cm^2$. 2. Before exposing to ultraviolet rays, the ergocalciferol contents of mushrooms were all $0{mu}g/g$ dry base, but after exposing to it , those of Lentinus edodes, Pleurotus ostreatus and Agaricus bisporus were $222.50{pm}5.30{mu}g/g$ dry base, $150.90{pm}6.60{mu}g/g$ dry base and $23.98{pm}1.20{mu}g/g$ dry base, respectively 3. Before and after exposing to ultraviolet rays, the riboflavin contents of Lentinus edoes, Pleurotus ostreatus and Agaricus bisporus were $18.22{pm}0.71{mu}g/g$ dry base and $11.72{pm}0.50{mu}g/g$ dry base, $4.57{pm}0.20{mu}g/g$ dery base and $3.26{pm}0.15{mu}g/g$ dry base, and $37.42{pm}1.20{mu}g/g$ dry base and $27.33{pm}2.10{mu}g/g$ dry base, respectively. 4. The ergocalciferol contents of mushrooms according to boiling time were not significantly different but the riboflavin contents of them were decreased according to the increase of boiling time. 5. The ergocalciferol and riboflavin contents of mushrooms were decreased according to the increase of NaCl concentration and baking temperature. 6. The ergocalciferol content of Lentinus edodes after a short time soaking at $80^{circ}C$ was higher than a long time soaking at $20^{circ}C,;40^{circ}C$ and $60^{circ}C$.