Written language errors can occur in BIPA learning due to several factors: students’ low grammar mastery, lack of understanding in word meaning, lack of competence in sentence forming linguistic units in Indonesian language, and influence of mother-tongue/native language in the use of Indonesian language. This research aims to describe the form of diction error, affixation, punctuation, and sentence structure in sentences written by BIPA level 2B students in Wisma Bahasa Yogyakarta. Based on 224 sentences on the questionnaire, there are 50 sentences with 80 language errors made by students. The most common language error is the use of particles in the aspect of diction, comprising 61.25%. Diction error include errors in verbs, nouns, adjectives, adverbs, numerals, particles, and clitics. In affixation section, the errors consist of 6.25% of the total errors, including prefix, suffix, and confix. Punctuation error occurs 20%, include errors in dot and comma use. Sentence structure errors cover as much as 12.5%, including subjects, predicates, and adverbs. The present study is expected to be beneficial to enrich the learners’ knowledge of morphology and syntax in BIPA learning level 2B in Wisma Bahasa Yogyakarta or at another BIPA institution. Furthermore, BIPA teachers can also take into account learning materials that potentially contain possible language errors to anticipate more language errors and sentence ineffectiveness.