NOVELTY - Manufacture of metal microparticles supported catalyst component involves supporting core-shell structure metal microparticles on carrier which is an electroconductive material. The core-shell structure metal microparticles comprise shell portion which is a noble metal, and core portion which is base metal. The core-shell structure metal microparticles comprise shell portion which is a noble metal, and core portion which is base metal. The core portion is obtained by producing the microparticles of base metal by reducing compound containing the base metal element in reaction liquid.    USE - Manufacture of metal microparticles supported catalyst component used for electrode of polymer electrolyte fuel cell.    ADVANTAGE - The method economically provides metal microparticles supported catalyst component having excellent catalytic activity and favorable particle size.    DETAILED DESCRIPTION - Manufacture of metal microparticles supported catalyst component involves supporting core-shell structure metal microparticles on carrier which is an electroconductive material. The core-shell structure metal microparticles comprise shell portion which is a noble metal, and core portion which is base metal. The core portion is obtained by producing the microparticles of base metal by reducing compound containing the base metal element in reaction liquid in which the carrier is exist. The shell portion is obtained by forming noble metal microparticles on the surface of the base metal into the core portion by reducing compound containing precious metal element in the reaction liquid in which the microparticles of the base metal are produced by the carrier and the core portion is produced. The core part production process and/or shell portion formation process is carried out using merging mixer provided with merging portion in which one pair of upstream flow paths is connected from one pair of upstream opening to the merging portion and the pairs of upstream flow paths are connected, and downstream flow path which connects the merging portion of downstream opening.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart explaining the manufacture of metal microparticles supported catalyst component. (Drawing includes non-English language text)    Primary mixing process (P1)    Secondary mixing process (P2)    Primary aging process (P3)    Tertiary mixing process (P4)    Secondary aging process (P5)