Reading is goal's area and learning's activities in Korean Language Education. It is important to know reading 'What' and 'How' in Reading teaching. In modern review, it is considered that reading makes meaning in text. Accumulated poor progress in reading are related to another subject, understanding level and thinking power. This article aims to study what is cause, what is diagnosis method, how to teach for disabled reader. The main contents of this are as follows : The causes of reading disability become known at external factors(environment), internal factors(recognition, emotion) and complex factors. Reading's failure types are shown up disability in vocabulary knowledge, in sentence structure's understanding, in sentences' relations and in meaning of the texture and so on. We diagnose and teach disabled reader according to their properties. It is called that teacher and disabled reader have to unit their efforts. And teacher have cause to them learning motivation. Therefore teacher must offer variable materials to them in succession, and must instruct repeatedly.