This study aimed at (1) analyzing the types of interlanguage errors in English writing assignment committed by 2nd semester students at STKIP Agama Hindu Singaraja, Bali, (2) analyzing dominant type of interlanguage errors in English writing assignment committed by 2nd semester students at STKIP Agama Hindu Singaraja, Bali, (3) describing the causes of interlanguage errors. The method applied is descriptive qualitative in nature with the subjects were 33 students of 2nd semester in academic year 2020/2021 at STKIP Agama Hindu Singaraja, Bali. The methods were used in this study were identifying the errors, classifying the errors, describing the frequency of errors, describing the dominant type of errors, and describing the causes of errors. There were 70 errors which are divided into three main categories, namely: morphological level (62), syntactical level (5), and discourse level (3) according to James (1998). The dominant type of error in this study was the word spellings in morphological level with the total number of errors were 46 errors. The causes of interlanguage error in students? writing namely interlingual transfer. Interlingual transfer is influenced by the structure of mother tongue.

Interlanguage error; ESL student; English writing