The present invention provides a protein-immobilized carrier which can realize highly efficient use of an immobilized antibody and prevent non-specific binding. A protein-immobilized carrier including a porous body having mesopores characterized in that the carrier has mesopores having an organic substance adsorbed therein other than an antibody, an antigen or a fragment thereof having a particle size smaller than the pore size of the mesopores and having an antibody, an antigen or a fragment thereof physically adsorbed and immobilized from the pore entrance to a depth of not more than the pore size in the depth direction of the mesopores.