A series of successful ion-propelled missions opened a new era of space exploration and development using high-Isp ion engines. Modifications and improvements of the current ion engines and the development of new ion engines are underway to enhance mission performance using ion engines. However, the life qualification tests for ion engines are difficult, time-consuming, and costly processes, which is a serious problem for the future use of ion engines. Therefore, the numerical evaluation of ion engine life has become very important. In 2006, JAXA started the JAXA Ion Engine Development Initiative (JIEDI) project to develop a numerical tool for the life qualification of ion engine optics. The developed code (JIEDI-1) can analyze the wear of the grid system caused by ion and neutral sputtering with a reasonable computational time. In this paper, the JIEDI-1 code is explained in detail and several examples of its use are presented.