To provide a pump unit eliminating solidification of a liquid in the starting and a liquid jet device having the same.

Before a user starts a printer 1 from a non-use condition for a long time period, the user may open a paper supply tray 3 and a paper discharge tray. While the paper supply tray 3 is opened as in the drawing, a gear G4 of the paper supply tray 3 is rotated in a direction of arrow Y. Along with the rotation, a rail R is moved in a direction of arrow B and the gear G3 is rotated in a direction of arrow A. The driving force by the rotation of the gear G3 is transmitted to a driving gear in a gear pump GP via a driving shaft attached to the gear pump GP. As a result, the driving gear is rotated, and then a follower gear is rotated. By rotating the driving gear and the follower gear, it is possible to peel an ink which is adhered to the driving gear and the follower gear by staying to be dried in the gear pump GP.