This paper will describe the result of an investigation on pre-service teachers misconception of decimal numbers. Written test and interview data reveal pre-service teachers misconception abot decimal. Misconception involing interpretation of decimal with repeating digits incorrectlyassociated with rounding rules is particularly dominant. Prior learning experience which is mainly based on memorized rules without meaningful understanding is found as one of the factors for this misconception. The importance of developing meningful understanding of decimals relying on knowledge of decimal place value is highlighted.