Objective: The aim of this study is to investigate the attributing factors influencing usability of the mobile phones specifically designed for the elderly users. Efforts to identify factors that cause usability problems for the elderly users in using mobile phones can provide the groundwork for changes aimed at usability enhancement and design of interfaces of mobile phones. Background: It became important to understand the behaviors and tendencies of the elderly in communication as the society became older. The problems in digital divide is contributed to mainly lack of understanding in terms of the use pattern of the elderly and lack of consideration of their characteristics in designing user interfaces of most ICT devices. Method: A total of 30 elderly users who were over 65 years in age participated in usability evaluation test experiment and performed seven different tasks using a widely accepted model of universally designed mobile phone. Their performance was compared with that of contrast group that consisted of 10 younger participants who were on their 20s. Results: It was found that the elderly users had hard times in using mobile phones, especially in keypad manipulation among search, understanding, and manipulation subtasks. Conclusion: Older users seemed to have difficulty in all the subtasks of search, recognition, and manipulation. It was suggested that designers of mobile phones need to give careful consideration into designing visual interfaces for search tasks and keypads for easier control and input for the elderly users. Application: The study is expected to provide guidelines for the universal design of mobile phones and their interfaces for enhancing usability of the mobile phone for elderly users.