Provided is a blood pump controller capable of preventing an operation error in performing a battery exchange with a small-sized and light-weighted configuration and exhibiting high waterproof property. A blood pump controller includes: a controller body for driving a blood pump； a battery pack having a first surface on which an electricity-supply-side battery connection connector is disposed and supplying stored electricity to the controller body； and a battery housing body having a slot which has a second surface on which an electricity-receiving-side battery connection connector is disposed and in which the battery pack is housed and held. When the battery pack is housed in the slot, an electrical connection is made between a pair of the battery connection connectors, the first surface and the second surface opposedly face each other, and a first sealing member provides sealing such that the first sealing member surrounds the pair of battery connection connectors.
