To provide a solution sampling system with a minimum time lag for measurement capable of continuous use without changing a filter for a long time.

A sampling system for pumping up a solution from a solution tank, conveying the solution after a liquid-solid separation treatment by a filter into a measuring system and analyzing the solution in the measuring system comprising: a filter having a construction for filtrating only a part of the pumped-up solution and passing the remaining solution, and a pump mounted between the filter and the measuring system whose direction of rotation may be reversed to enable baskwash of a filtration surface of the filter. The sampling filter for use in the system comprising: a top lid, a bottom lid, a body part and a filter element; the body part being provided with an opening for taking out a filtrate, the top lid being provided with a discharge port of the solution, and the bottom lid being provided with a suction port of the solution, respectively; the top lid and the bottom lid being constructed detachable from the body part; the filter element being sealed in the body part and the top lid and the bottom lid being attached such that a part of the solution flowing between the suction port and the discharge port may be filtrated by the filter element.