This paper tries to measure the information asymmetry of Korea automotive market. Warranty of secondhand car market is assumed as proxy variable of information asymmetry in the paper. There is no country has institution such as government secondhand car market warranty. So, we can say that warranty of Korea secondhand car market is unique institution. Stated preference data were using for measuring WTP (willingness to pay) for attributes of secondhand car including warranty and collected by being based on conjoint analysis. Collected consumer stated preference data were analyzed using mixed logit model. 2670 data were used for this analysis and simulation set 1000 random draws was operated for each datum. As results of estimation, WTPs for ``year`` and ``mile`` are 730,000￦ and 1,290,000￦ respectively. And WTP for warranty is estimated to 4,890,000￦. This huge WTP for warranty seems to reflect information asymmetry of Korea secondhand car market.