In this paper, a mobile system is designed and implemented for children with learning disabilities. The system is designed to improve reading skills of those students. The reading skill is very basic and essential ability for various subjects. In this paper, the proposed mobile system is based on PREP that is known as a good theory for improving reading skills of children with learning disabilities. The system has the following characteristics. First, the system can improve the reading skills by providing successive tasks and simultaneous tasks. Second, the system can provide interests by introducing quiz-type study and considering accessibility, and individuality of learning disorder students. Third, the system has user-friendly interface so that the students have easy access to the system. The system is applied to some elementary school students. The following result is obtained: both of reading attitude and reading ability are improved.