Nowadays, the number of smartphone users is growing rapidly. Recent smartphones equipped with several sensors are convenient tools for collecting information in participatory sensing environment. However, contributing sensing data require time and monetary cost which hinder may people from participation. To realize active and efficient sensing activities, incentive mechanism is indispensable. This paper proposes SenseUtil, utility-based incentive for participatory sensing. SenseUtil applies the concept of micro economics, where demand and supply decide the value of sensed data. The incentive dynamically changes along the time according to several factors such as sensing frequency, nearby sensing points and user preference. To validate the benefit of SenseUtil, we conducted simulation study. The results show that people actively participate in sensing tasks while keeping additional cost under 3% in comparison with non-incentive scenarios. Keyword Participatory sensing, incentive, utility, phone sensing, SenseUtil, simulation.