The users are allowed to easily retrieve contents data such as recipe data. A personal computer (103) receives recipe data from a server (101) via a communication network (102), and stores the received recipe data in a memory card (104). The personal computer updates recipe hierarchical information (142) in the memory card (104), i.e., information which indicates classified levels of recipe data based on retrieval keys, with reference to overall hierarchical information (133), i.e., information which indicates the hierarchical relation of retrieval keys in the whole recipes, so that the newly stored recipe data is included in the recipe hierarchical information.