To provide a solid-phase carrier to which impurities are hard to nonspecifically adsorb. A solid-phase carrier, formed by binding a chain polymer, wherein the chain polymer comprises a random polymer structure containing a first structural unit having a reactive functional group, and a second structural unit having no reactive functional group or having a reactive functional group having a reactivity lower than that of the reactive functional group of the first structural unit, and the content ratio of the number of moles "a" of the reactive functional group contained in the first structural unit to the number of moles "b" of the entire structural unit contained in the chain polymer, (a/b), is from 0.01 to 0.7.
