The reversible transfer of Pd species between solvent and support occurs for Heck reactions of iodobenzene with methyl acrylate in N-methylpyrrolidone (NMP) using triethylamine and sodium carbonate as bases. When a homogeneous Pd catalyst was used with an additional support, the Pd species deposited on the support after the completion of reaction. Then Pd was easily separated from the reaction mixture, and it was successfully used for repeated reactions, which were mainly catalyzed by Pd species dissolved in solution, The transfer of Pd strongly depends on the surface nature of support materials and the reaction conditions used.