Provided is a blood purifier that comprises a porous molded body； that exhibits an excellent blood compatibility wherein platelet adherence is inhibited and exhibits a good cytokine adsorption capacity and a low pressure loss before and after blood treatment； and that can be safely used. Disclosed is a blood purifier that comprises a main vessel and a porous molded body housed in the main vessel. The porous molded body contains a hydrophobic polymer and a hydrophilic polymer. The amount of low-melting-point water per 1 g of dry weight of the porous molded body is 0.12 g to 2.00 g. The contact change ratio for the porous molded body is 0% to 0.2%. The ratio L/D is 1.00 to 2.30 where, for the region taken up by the porous molded body in the main vessel, L is the length in the flow direction and D is the circle-equivalent diameter of the cross section in the direction perpendicular to the flow direction. The circle-equivalent diameter D is calculated based on formula (A):D = 2√(V/L/3.14) (A).In formula (A), V is the apparent volume of the region taken up by the porous molded body in the main vessel. In addition, when an aqueous polyvinylpyrrolidone solution with a viscosity adjusted to 3.75 mPa·s to 3.85 mPa·s is flowed through the blood purifier at a flow-through rate of 400 mL/minute, the pressure loss of the blood purifier before blood treatment is less than 13 kPa and the pressure loss of the blood purifier after blood treatment is less than 13 kPa.L'invention concerne un purificateur de sang qui comprend un corps moulé poreux； qui présente une excellente compatibilité sanguine dans laquelle l'adhérence des plaquettes est inhibée et présente une bonne capacité d'adsorption de cytokine et une faible perte de pression avant et après le traitement du sang； et qui peut être utilisée en toute sécurité. L'invention concerne un purificateur de sang qui comprend un récipient principal et un corps moulé poreux logé dans le récipient principal. Le corps moulé poreux cont
