A blood purification device includes: a control device that controls supply of a dialysis solution to a blood purifier； a dialysis solution supply tube in which a dialysis solution flows from the control device toward the blood purifier； a dialysis solution discharge tube in which the dialysis solution flows from the blood purifier toward the control device； a supply side coupler that connects between the dialysis solution supply tube and a dialysis solution inflow pipe of the blood purifier； and a discharge side coupler that connects between the dialysis solution discharge tube and a dialysis solution outflow pipe of the blood purifier. At least one of the supply side coupler and the discharge side coupler includes a light source unit configured to irradiate the interior of the coupler with ultraviolet light.
