This study aims to verify the effectiveness of English language materials using mobile devices for business people in terms of the effect on motivation, overall learning performance, and practical performance in real business situations. We compared the use of materials developed from business English for a sales department in a company environment, using two cohorts of learners, one from the sales division and the other from other divisions in the company. The results showed that the materials were effective for the enhancement of motivation in both groups of employees. Moreover, the test scores in overall learning performance for both cohorts increased after learning with the materials. However, the learners in sales positions recognized the effectiveness of the output activities (e.g., speaking) more than that of nonsales personnel because of the direct applicability of the learning materials to their business needs. (Contains 5 tables and 3 figures.)