To characterize testing bags for the interior parts and components of new vehicles, three types kinds of bags (Tedlar bag, Polyester Al bag, and PET bag) were selected and investigated.. All testing bags were initially purged with 5 L of pure nitrogen gas. Then, they were heated consecutively for four times in a chamber at 60 and 100℃ at hourlys intervals. Changes in background concentration levels of VOCs and HCHO were then measured. After the 4th heat treatment at 100℃, the background concentrations in PET bag were lower by 5 times than the ftrst time treatment. The results of PET bags were superior to the other bags under the same treatment conditions. Even without heat treatment test, the background concentrations of PET bag was also lower than the others by 2 to 6 times. Based on our results, it can be concluded that the PET bag is the most suitable for sample tests as it is physically the most stable along with the lowest background of all 3 sample bags with the least bias.