A check valve is provided between an inflow pipe and a discharge pipe through which fluid is transferred. The check valve includes a body part having an inflow region connected to the inflow pipe so that the fluid flows therein, a retention region in which the fluid supplied therein through the inflow region remains, and a discharge region connected to the discharge pipe so that the fluid of the retention region is discharged to the outside therethrough; and an opening/closing part, which is provided inside the body part so as to have a disc assembly for opening/closing the path of the fluid flowing in through the inflow pipe, a stem for providing the movement path of the disc assembly, and a first guide for supporting one side of the stem.