A test kit for intracellular introduction of a protein and/or peptide and a method of such intracellular introduction, make it possible for a protein and/or peptide to be introduced into cells efficiently and in an expedient manner while preventing the function of the introduction target protein and/or peptide from being reduced. The above test kit comprises a container containing a cationic group-containing polymer and a container containing a reagent for coupling or binding the cationic group-containing polymer to the protein and/or peptide, or comprises a container containing a cationized conjugate to be coupled to the protein and/or peptide. The above method comprises using a conjugate generated by coupling or binding a cationic group-containing polymer to a protein and/or peptide as a carrier for the introduction target protein and/or peptide.