A blood purification device 10 includes: a control device 50 that controls supply of a dialysis solution to a blood purifier 20； a dialysis solution supply tube 66 in which a dialysis solution flows from the control device 50 toward the blood purifier 20； a dialysis solution discharge tube 68 in which the dialysis solution flows from the blood purifier 20 toward the control device 50； a supply side coupler 30a that connects between the dialysis solution supply tube 66 and a dialysis solution inflow pipe 26 of the blood purifier 20； and a discharge side coupler 30b that connects between the dialysis solution discharge tube 68 and a dialysis solution outflow pipe 28 of the blood purifier 20. At least one of the supply side coupler 30a and the discharge side coupler 30b includes a light source unit configured to irradiate the interior of the coupler with ultraviolet light.
