An inspissator is provided. The inspissator used for concentrating protein aqueous solution generated by filtrating coelomic fluid can realize the concentration with high magnification and can guarantee the high recovery of protein. The separating membrane (60) of the inspissator (22) has the porosity of more than 60% and less than 80%, and the raising value of the liquid level of the separating membrane measured with a capillary rise method is 60mm-150mm when convert the value into the hollow fiber membrane with inner diameter of 200 mum. The conditions (1) and (2) are met, when performing the concentration process of the concentrated solution of the protein aqueous solution obtained by flowing the protein aqueous solution stoste with the concentration of 3g/dL at the flow velocity of 50Ml/min. (1) the maximum pressure difference between membranes of concentration of 5L protein aqueous solution stoste is less than 500 mmHg, and (2) the pressure difference between membranes of concentration of 2L protein aqueous solution stoste is A, and the pressure difference between membranes of concentration of 5L protein aqueous solution stoste is B, B/A<=1.6.