The construction of apartment takes a long time, so the developers often do the marketing before the construction was done. This method was usually called pre-project selling. In this method, the developers and the buyers will make sale and purchase binding agreement as an initial stage of sales. However, this has caused many problems such as the developer was declared bankrupt before the construction was even completed yet. The issue that will be discussed in this research is how to sell the property rights of apartment units when the apartment building has not been completed and how is the legal protection for buyers of apartment units if the developer is declared bankrupt based on Supreme Court Decision Number 253/K/Pdt.Sus/2012 regarding the Kemanggisan Residence Apartments. The research method used in this paper is normative legal research using secondary data. The data was obtained from library research data. The types of approaches used are the statute approach and the case approach. The analysis of the data obtained was done qualitatively. Based on the research results, it was found that sales of the apartment units before the building was completed was carried out through an order letter and sale and purchase binding agreement as the initial stage of sales after meeting certain requirements, which would be followed by deed of sale and purchase after the building was completed. It was also found that if the developer went bankrupt, the buyers had a weak position as concurrent creditors so that they were greatly disadvantaged and lacked legal protection. This shows that the existing regulations have not been able to protect the rights of the buyers when the developer was declared bankrupt.