Objectives This study investigated the effectiveness of the intervention program for elementary school students with reading disorders. Methods The intervention program focused on phonological awareness, phonics, and decoding training applied individually to 25 children with a reading disorder by the teachers in charge for four months. To measure the efficacy, this study evaluated the word reading accuracy, fluency, and the related cognitive functions, including phonemic awareness, phonics, and rapid automatized naming using the Computerized Comprehensive Learning Test-Reading before and after the program. Results After the intervention, improvements were observed in the following: the reading fluency score and fluency percentile in the word attack test; reading accuracy rate, fluency score, and fluency percentile in the nonword decoding test; fluency score and fluency percentile in the rapid automatized naming tests; accuracy rate in the letter-sound matching test; accuracy rate in the nonword repetition test. On the other hand, there was no significant difference in the paragraph reading fluency test. According to the subtypes of reading disabilities, children with dyslexic or mixed types improved after the intervention. Conclusion Reading accuracy and fluency of school-aged children with reading disorders improved through the intervention program by the schoolteachers.