When an active volcano erupts, a restricted area is typically imposed around the crater of the volcano to protect people from volcanic phenomena. On the other hand, it is important to make observations inside the restricted area, to initiate alarms and make evacuation plans. Therefore, research and development of unmanned volcano exploration robots have been carried out all over the world. However, although ash sampling in restricted areas is an urgent necessity, there is no quick sampling method. Therefore, in this study, we aim to realize a sample-return system that uses a multi-rotor unmanned aerial vehicle (UAV) for obtaining volcanic products. In this paper, we introduce two sampling devices that we developed, and report results of indoor sampling experiments and outdoor field tests.