1. A mobility pattern mining device, comprising: a data collecting unit configured to collect a user's historical data; a stay point obtaining unit configured to obtain stay points of the user from the historical data; an extracting unit configured to obtain a semantic tree for a certain topic and extract topic related stay points from the stay points of the user by using the semantic tree for the certain topic; a determining unit configured to determine a candidate mobility pattern of the user based on the topic related stay points; and a selecting unit configured to select a frequent mobility pattern which best matches the candidate mobility pattern of the user from a frequent mobility pattern database related to the certain topic; wherein the frequent mobility pattern database is set in advance based on historical data for a plurality of users.