A concentrator comprising: a filtering device having a case provided with a filtration membrane in an internal space, an inflow port and a first outflow port bringing an inside of the filtration membrane and an outside of the case into communication with each other, and a second outflow port bringing an outside of the filtration membrane and an outside into communication with each other, wherein the filtering device is disposed so that an inflow port and a first outflow port each face a direction crossing the rotation axis a liquid supply circuit connected to the inflow port; a liquid discharge circuit connected to the first outflow port and the second outflow port; a first rotation mechanism configured to rotate the filtering device so that positions in a vertical direction of the inflow port and the first outflow port are changeable, a culture vessel having a first port and a second port bringing an internal space and an outside into communication with each other; a first reservoir having a third port bringing an internal space and the outside into communication with each other; a collection vessel having a fourth port bringing an internal space and the outside into communication with each other; and a liquid supply/discharge mechanism having a switching mechanism configured to switch flow passages in the liquid supply circuit and the liquid discharge circuit, a first pump configured to circulate a liquid in the liquid supply circuit, and a second pump configured to circulate a fluid in the liquid discharge circuit, wherein the liquid supply circuit is connected to the first port, the inflow port, and the third port so that the flow passages are switchable, and the liquid discharge circuit is connected to the second port, the first outflow port, the second outflow port, and the fourth port so that the flow passages are switchable, wherein the first rotation mechanism is configured to rotate the culture vessel so that the positions in the vertical direction of the first port and the second port are changeable and configured to integrally rotate the culture vessel and the filtering device. a filtering device having a case provided with a filtration membrane in an internal space, an inflow port and a first outflow port bringing an inside of the filtration membrane and an outside of the case into communication with each other, and a second outflow port bringing an outside of the filtration membrane and an outside into communication with each other, wherein the filtering device is disposed so that an inflow port and a first outflow port each face a direction crossing the rotation axis a liquid supply circuit connected to the inflow port; a liquid discharge circuit connected to the first outflow port and the second outflow port; a first rotation mechanism configured to rotate the filtering device so that positions in a vertical direction of the inflow port and the first outflow port are changeable, a culture vessel having a first port and a second port bringing an internal space and an outside into communication with each other; a first reservoir having a third port bringing an internal space and the outside into communication with each other; a collection vessel having a fourth port bringing an internal space and the outside into communication with each other; and a liquid supply/discharge mechanism having a switching mechanism configured to switch flow passages in the liquid supply circuit and the liquid discharge circuit, a first pump configured to circulate a liquid in the liquid supply circuit, and a second pump configured to circulate a fluid in the liquid discharge circuit, wherein the liquid supply circuit is connected to the first port, the inflow port, and the third port so that the flow passages are switchable, and the liquid discharge circuit is connected to the second port, the first outflow port, the second outflow port, and the fourth port so that the flow passages are switchable, wherein the first rotation mechanism is configured to rotate the culture vessel so that the positions in the vertical direction of the first port and the second port are changeable and configured to integrally rotate the culture vessel and the filtering device.