Provided are a stock solution concentrating device, a stock solution treatment device and a circulation-type treatment device that can prevent the deposition of cells and the like on a filtration member and that can continuously filter and concentrate a stock solution such as pleural and ascitic fluid, and blood plasma. The stock solution concentrating device concentrates a stock solution such as pleural or ascitic fluid or blood plasma to form a concentrated solution, and is equipped with: a filter (10) having a filtration member that filters the stock solution a concentrator (20) to which the filtrate which has been filtered is supplied, and which concentrates the filtrate to form a concentrated solution and a stock solution supply unit that supplies the stock solution to the filter (10). The stock solution supply unit has a supply amount adjustment function for adjusting the amount of the stock solution supplied to the filter. Thus, a concentrated solution can be obtained having a high concentration of an active component and without a cell component. The efficiency with which a stock solution such as pleural or ascitic fluid or blood plasma can be treated is increased by treating the stock solution at a flow rate at which the filtration member is not susceptible to the deposition of cells or the like.La présente invention concerne un dispositif de concentration de solution mère, un dispositif de traitement de solution mère et un dispositif de traitement de type à circulation permettant dempêcher le dépôt de cellules et équivalents sur un élément de filtration et pouvant filtrer en continu et concentrer une solution, par exemple le fluide pleural, le liquide ascétique, et le plasma sanguin. Le dispositif de concentration de solution mère concentre une solution mère telle que le fluide pleural, le liquide ascétique ou le plasma sanguin pour former une solution concentrée, et est doté de : un filtre (10) ayant un élément de filtration qui filtre la solution mère un
