Basic gymnastics skills are needed in PJOK lessons. The purpose of the study is to develop an application-based self- assessment instrument to improve the ability to roll forward, roll backward, wax attitude, and kayang. The type of research is research and development (Research and Development) The population of this study includes all students of SD Negeri 2 Tanjung Gadang class VI as many as 25 students, and SD 15 Teratak Baru class VI as many as 30 students with a total of 55 students. The samples in the study were all students of SD Negeri 2 Tanjung Gadang class VI as many as 25 students, and SD 15 Teratak Baru class VI as many as 30 students. The sampling technique is total sampling. Analysis of research data is carried out after data collection is completed to find out the assessment of the products that have been developed. There are three steps in conducting data analysis, namely: (1) Preparation, (2) Tabulation, and (3) Application of data by the research approach. The instrument used to collect data in testing the development of this product is to use non-test instruments. The instrument is made in the form of a structured questionnaire. The results of research on the development of application-based self- assessment for basic gymnastics evaluation are basic gymnastics self-assessment application media with a validation rate according to experts an average of 83.8% so the media can be said to be feasible. Then the reliability rate was up to 0.982 in small group trials and 0.974 in large group trials, so the tool is said to be reliable in evaluating basic gymnastics based on self- assessment applications. The conclusion is that the name of the basic gymnastics self-assessment application media is said to be reliable in evaluating basic gymnastics based on self-assessment applications.