A method for manufacturing a wet master batch, includes preparing a carbon black slurry by dispersing carbon black in water, mixing a rubber latex and the carbon black slurry to cause a coagulation reaction to occur, to obtain a coagulation slurry, and subjecting the coagulation slurry to solid-liquid separation and dehydration, wherein the solid-liquid separation and dehydration comprises: filtering the coagulation slurry through a filter by gravity and depressurizing; and pressing the coagulation slurry thus filtered against an outer peripheral surface of a drum by a pressing portion, thereby pressure dehydrating the coagulation slurry. Further, a solid-liquid separation and dehydration device for manufacturing a wet master batch has a filtration filter, a filtration portion, a drum, and a pressing portion. According to the aforementioned method and device, solid-liquid separation and dehydration of a coagulation slurry containing a coagulated substance having relatively small particle can be achieved in an efficient manner.