This study evaluated release of the residual monomer and cytotoxicity after polymerization of three denture base resins (heat curing resin, self-curing resin, light curing resin by 3D printer). Three types of resin specimen according to the manufacturer’s guideline were fabricated: heat curing resin (Group H), self-curing resin (Group S), 3D Printed resin (Group L). Each group of specimen were stored in distilled water at 37 ℃ for 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks in order to measure the release of the residual monomer. Absorbance was measured at each storage time in the three groups. Cytotoxicity is measured by MTT test at each storage time in the three groups. For statistical analysis, one-way ANOVA with post-hoc tests of Dunnett T3 test and Scheffe test were carried out, where p values of less than 0.05 were considered as significant. Group H showed the lower absorbance than Group S and Group L. There was no statistically significant difference in the absorbance of Group S and Group L for 8 weeks, except for the one day. Group H and Group S showed no cytotoxicity, but Group L resulted in cytotoxicity. To conclude, light curing resin used in 3D printer revealed high cytotoxicity in this study. In order to apply the 3D printed denture base resin to clinical situation, it is necessary to develop a method to reduce the release of residual monomers.