PTSL activities are different from other land registration activities, where the objects are not only unregistered land which are categorized as K1, K2 and K3 plots, but also that have been registered land categorized as K4 plot for data quality improvement. The K4 data condition that needs attention is the registered land that have not been mapped on the Registration Map or spatially in the GeoKKP. In implementation, improving the quality of this data often encounters problems that need to be found solutions so that activities to improve the quality of K4 data run
smoothly. The location of the research was carried out at the Sleman Regency Land Office, where in 2019, the realization of the mapping of K4 PTSL land was 34,534 land .
This study aims to determine the condition of the K4 PTSL data quality KW4 - KW6, the procedures for improving the quality of data through improving the K4 PTSL and improving the quality of the data as well as problems and solutions in the implementation of improving the quality of K4 PTSL of KW4 - KW6 in the Sleman Regency Land Office. The research method used is descriptive method with a qualitative approach with data analysis including data reduction, data display and conclusion.
The results of this study are: First, the condition of data quality in Purwomartani and Bangunkerto Villages has increased, which respectively increased to 81.33% and 87.76% with the realization of K4 mapping of 5,303 and
250 plots. So that in general the condition of the data quality of the Sleman Regency Land Office in the KKP has also increased to 68.40% with the realization of the K4 mapping of 34,354 plots . Second, the increase in data quality did not reach a percentage of 100% which was caused by the implementation of improving the quality of data on the K4 PTSL plots encountered both technical and non-technical obstacles which then provided solutions to these problems.

Keywords: K4 plots, Improving the Qualilty of the Data, Problems and Solution