The effect of long-time heating for elements from flame retardants (FRs) such as dechlorane plus (DP), tetrabromobisphenol A (TBBPA), triphenyl phosphate (TPhP) and antimony trioxide (Sb2O3) in both acrylonitrile-butadiene-styrene (ABS) and polycarbonate (PC) resin disks was examined in the present study. The heating temperature by a drying oven was 80°C, which was expected to be a harder environment than that of usual dump site to discard electric and electronic equipment, and the long-time heating was carried out for up to 722 days. As a result, the increases for both ether (C-O-C) and ketone (C=O) groups and the decrease of C=C double bond as well as methylene group (=CH2) were found for an ABS resin disk by fourier transform infrared (FTIR) spectrometry, which was expected to result in an increase of mass of the disk up to ca. 4% due to oxidation during the long-time heating. The changes in concentrations for bromine (Br), chlorine (Cl), phosphorous (P) and Sb, which were originated elements from FRs contained, were also evaluated by energy dispersive X-ray fluorescence (ED-XRF) spectrometry and the decreases in concentrations of ca. 5% in ABS resin disk were observed which could be almost explained by increasing ca. 4% mass of the disk. On the contrary, the mass and chemical form of a PC resin disk as well as the concentrations of elements contained did not change during the long-time heating. From these results, it could be considered that most of the elements from DP, TBBPA, TPhP and Sb2O3 contained as FRs in the ABS and PC resin disks examined in the present study were not lost during the long-time heating, even though the color, shape, mass and chemical form of ABS resin disk were changed.