A method and an apparatus for encoding and decoding a modulation code are provided. The method includes: adding an error detection bit(s) to source information; performing k-constraint coding by inserting an error pattern that can be detected using an error detection code into a data stream that violates a k-constraint for a run length limited (RLL) code in a data stream comprising the error detection bit(s) and the source information, and recording the data stream after being k-constraint coded onto a recording medium; and reading the data stream recorded onto the recording medium and determining whether an error is present in the data stream.