The purpose of this study was to investigate the effect of secondary heat treatment on dimensional changes of acrylic resin partial denture base. For this study, 6 specimens were made: 2 groups of 2 specimens, each was treated with $125^{circ}C$ dry heat and glycerine heat for 3 minutes, and the others were prepared for control group. The change of the internal diameter of specimens were measured after 3 hrs, 1 day, 1 week, 2 weeks, 4 weeks by three-dimensional space analyzer. The results were as follows : 1. All of the acrylic resin denture bases showed tissue ward thermal contraction. 2. Thermal contraction of the mesial area reinforced with metal framework was lesser than that of the distal area without metal framework. 3. Thermal contraction of the lingual flange reinforced with metal framework occured more slowly than that of the buccal flange without the metal framework. 4. The thermal contraction of dry heat treated acrylic resin base, compared to glycerine heat group, was moderately greater and occurred acutely.