Disclosed is novel means for producing a platelet solution replaced with an artificial preservation solution, which means has a platelet-activation-suppressing performance, high platelet recovering performance, and high blood-plasma-removing performance. The method for producing a platelet solution replaced with an artificial preservation solution of the present invention comprises: a filtering step of carrying out cross-flow filtration of a platelet solution under the conditions of Formula 1 described below at an inlet wall shear rate of 25 to 1500 s -1 using a separation membrane whose surface which contacts with the platelet solution has an average pore size of not less than 0.1 µm and less than 2.0 µm, thereby obtaining a concentrated platelet solution and a mixing step of mixing the concentrated platelet solution with an artificial preservation solution to obtain the platelet solution replaced with an artificial preservation solution. A: Concentration of platelets contained in the platelet solution (platelets/mL with the proviso that the range is 8.0×10 7 to 200×10 7 platelets/mL) B: Filtration flow rate per unit area (mL/hr/m 2 ) ³: Inlet wall shear rate (s -1 ) µ P : Viscosity of the platelet solution (Pa·s)
