The evaluation on the policy PR activities is a very important work for the development of future PR activities. Accordingly, it is also significant for clients who want to know how effectively the budget spent for PR has been used, and how effective an activity is. The accurate and objective measurement on the effectiveness of PR is also high in the importance in the aspect of efficient management of government budget. Although studies about the effectiveness utilizing mobile apps have been performed in various areas as the current media environment changes to mobile environment, they have been limited studies in the aspect of advertising and health behavior management and the studies about the effectiveness in the field of policy PR have been rare. As such, for coming up with the future direction for the development of mobile apps managed as tools for policy PR, the present study selected a mobile app and examined the effectiveness of communication. Especially, this study attempted to explicate the implication for the applicability of mobile application by investigating how variables such as the evaluation about app features, app engagement, task-media fit evaluation influence the effectiveness of policy PR. Methodologically, the current study asked respondents to write down the questionnaires including measurement scales for each variable after performing the DIY usability evaluation about a mobile app operated by the Employment and Labor Ministry. As a result, values of components such as credibility, comprehensiveness, evaluation for communication, etc representing the outcome of policy PR has shown positive changes after usability evaluation. Even though information did not have significant influence on the effectiveness of policy PR, interactivity had indirect influence on the policy PR effectiveness through mediation by the satisfaction factors of app engagement.