A flow-controlling unit provided in a flow channel is disclosed. The flow-controlling unit provided in a flow channel, according to one embodiment of the present invention, comprises: a plate which is disposed perpendicular to the moving direction of a fluid in a flow channel, and on which are formed multiple fluid through-holes through, which the fluid passes; and one or more flow-controlling pieces which are provided in a position corresponding to the fluid through-holes, form an inclination with respect to the plate in the direction of the inflow of the fluid, are capable of tilting on the plate, and control the degree of opening of the fluid through-holes by being tilted due to pressure applied from hydraulic pressure of the fluid.