The aim of this study was to clarify the erosion behavior of light-cured glass ionomer cement. One light-cured glass ionomer cement and two conventional chemically-cured glass ionomer cements were immersed in citric acid buffer solutions of pH 4 and pH 6. Fluoride release was almost the same in both types of cements, irrespective of pH. The amounts of other species eluted, such as Al, Sr, Si and P₂O₅ were smaller in the light-cured glass ionomer cement than in the conventional ones at pH 4. The amounts of species eluted at pH 6 were almost the same in both types of cement. Dissolution of the light-cured cement in pH 4 solution was controlled by the diffusion of the eluted species in the cement matrix. On the other hand, dissolution of the conventional cements was controlled by both diffusion and surface reaction. The surface features of the cements after erosion corresponded well to the dissolution mechanism. In pH 6 solution, dissolution of the cements was mainly controlled by diffusion of the species in the cement.