Like other countries, Vietnamese households in urban area have higher saving rate than those in rural. Hence, there would be a saving rate gap between urban and rural in fact. Yet, this gap has not been investigated before. In this paper, we expect to reveal this gap by analyzing the household saving rate difference between urban and rural sectors at the means and at the unconditional quantiles to find out what are the determinants causing this difference. To aim this objective, we apply Oaxaca-Blinder decomposition method on the results of OLS and unconditional quantile regressions to divide the gap or the difference into two contribution components: the endowment effect and the return effect. First of all, we find that the urban - rural saving rate gap between urban and rural households decreases monotonically from the low to high quantiles of distribution. Additionally, at the low quantiles, the component of endowment effect plays important role in enlarging the gap. Nevertheless, at the high quantiles, the component of return effect has a crucial impact in decreasing it. Obtained from the detailed decomposition, we find that household income is the most important factor for both the endowment and return effect. As a result of this study, we suggest that policies related to household income could be applied to limit the saving difference between two areas.