On January in 2013, a district judge made a constitutional suit to the Constitutional Court whether voluntary prostitution is unconstitutional. The key point is that the legal interest of the punishing voluntary prostitution is obscure, to punish it is not accorded with the properness of manner and the minimum of victim, and it is questionable in point of equal protection. The question that voluntary prostitution is unconstitutional is during debate since long time ago. Some says it should not be punished because everybody has a sexual self-determination, others it is crime because it is immoral, and the others it is controlled by the state because it is harmful to the moral people. I make a couple of proposals in the following points. Firstly, because the legal interest of punishing voluntary prostitution is obscure, so that it should not be punished. Secondly, punishing voluntary prostitution is unconstitutional because everybody has a sexual self-determination and buying or selling sexual service is absolutely depending on the individual. Thirdly, punishing voluntary prostitution is out of the principle because it goes against with the ultima ratio rule. Fourthly, punishing all the patterns of voluntary prostitution is not possible and punishing some peculiar types of prostitution does not accord with equal protection. Finally, punishing voluntary prostitution is against the principle of less restrictive alternative because everybody has a right to have a sex without force with another. So punishing voluntary prostitution is unconstitutional. However, if the Constitutional Court proclaims that it is unconstitutional, it would give a shock to the ordinary people because they do not have an open mind with it. So I dare to say that punishing voluntary prostitution is committed to the ‘factual’ decriminalization for a while before punishing adultery is unconstitutional proclaimed by the Constitutional Court.