This paper proposes a new cache management method considering the popularity of contents for in-network caching. In networks with in-network caching, routers store contents in their cache and users can download them from the routers. By utilizing cached contents, the loads for content servers and networks can be reduced. The proposed method provides a distributed cache management strategy that aims at utilizing unpopular contents in addition to popular contents. Through simulation experiments, we show that the proposed method enhances the cache utilization efficiently.