This study aims to determine: ( 1 ) the types of mistakes students make; and ( 2 ) the factors that caused the mistakes of fifth grade students of SD Manukan Wetan 1 Surabaya in solving the calculation operation problems in the division of decimal fractions . The subjects in this study were class V as many as 29 people, and the subjects interviewed consisted of 3 people. The results showed that the types of errors and the factors causing errors made by students in solving the problem of decimal fraction division are as follows: Types of conceptual errors, the causal factors namely Factors causing the errors are: ( 1) Subjects have not been able to apply the meaning of division to the fractions of 29 people student test takers, there are around 12 students or 41.38% who make mistakes. ( 2 ) Complete the completion operation. Of the 29 students who took the test, there were about 14 students or 48 , 97 % made mistakes. (3 ) Turn ordinary fractions into decimal fractions / Determine the final result. Of the 29 students who took the test, there were about 20 people or 69 , 66 % made mistakes.

Keywords : Error Analysis , Division of Decimal Fractions.