To facilitate and ensure the supply of a highly viscous fluid such as industrial chemicals such as solvent, printing ink, paint, adhesive, oil and the like.

This pump has an inlet pipe 5 and a discharge pipe 12 adjacent thereto. The inlet pipe 5 has a suction opening 2 in the lower part and an expansible cylindrical part 6 having a bellows shape and vertically expansible and contractible on the upper end. The suction opening 2 is openable and closable by a first valve 9. An inflow port 11 provided in the lower part of the discharge pipe 12 is openable and closable by a second valve 15, and the inflow port 11 is allowed to communicate with the lower end part of the inlet pipe 5.