Traditional approach to analyze the determinants of Chonsei deposit to housing sales price ratio is based on asset market equilibrium condition. However, this approach does not fully account for complexity involved in Korean rental housing market, where Chonsei, Monthly-rent-with-variable deposit, and pure monthly rental contracts coexist. In this paper, we utilize each rental type’s different rate of return structure and examine the determinants of Chonsei deposit to housing sales price ratio based on rental housing market equilibrium condition. We further incorporate housing price volatility into the analysis as a critical variable related to housing investment risks, which has been ignored in previous studies. Our empirical analysis using a sample of the apartment sales price and rent in Seoul confirm our theoretical predictions: Chonsei deposit to housing sales price ratio is positively linked to the rent-to-price ratio and housing price volatility, and the ratio is negatively affected by the expected housing price appreciation rate. The relationship between the Chonsei deposit to housing sales price ratio and housing price volatility was robust to different measures of housing price volatility. The long-run elasticity of Chonsei deposit to housing sales price ratio with respect to rentto- price ratio was estimated to be 1.04~1.22 and the long-run elasticity of the ratio with respect to housing price volatility was estimated to be 0.15~0.53. which is about 50 to 100 percent of the long-run elasticity with respect to expected housing price appreciation rate. These results show that previously ignored housing price volatility is one of important variables to affect Chonsei deposit to housing sales price ratio and risk factors are needed to be considered to better understand Korean housing market.