Recent Advances in solid state and packaging technologies have enabled production of more efficient and reasonably small devices such as Micro Electro Mechanical Systems (MEMS). Wireless Sensor Networks (WSNs) can gather data from sensor nodes and are now at the practical stage of realizations because of the above advances. Conventional researches have mainly focused on extending the lifetime of WSNs because sensor nodes are only equipped with small-capacity batteries. Mobile Ubiquitous LAN Extension (MULE) is one of the approaches to meet such demand, and it can gather data from isolated nodes. The KAT mobility scheme is one of the mobility schemes on MULE focusing on the efficiency. Therefore, this scheme is expected to prolong the lifetime of the network. However, this scheme cannot ensure that the mobile sinks can gather the data from all of the nodes. In this paper, we focus on the fairness issue of data gathered by the mobile sinks while also considering the efficiency of data gathering. We propose a new mobility scheme based on a new clustering method and the Set Cover Algorithm to ensure that the mobile sinks can gather data from all of the nodes, and simulation results show that fairness of data gathering by the proposed mobility scheme is greatly improved as compared to conventional KAT mobility scheme.