This corpus is based on cross-sectional research and collects data on spoken and written words of 1000 Japanese learners of 12 different native languages. The title of this corpus is "International Corpus of Cross-sectional Research of Japanese learners", and the abbreviated title is "I-JAS (International Corpus of Japanese as a Second Language)". The targeted Japanese learners were requested to take the Japanese proficiency test to assess their langauge proficiency. Therefore, the data can be compared by level, native language, tasks, and learning environment. Examples can be searched online, along with audio data from speech research.