Provided are a composition for cell transplant and a method for cell transplant that allow myocytes and/or cardiac progenitor cells to be suitably maintained in myocardial tissue and allow the survival and proliferation of transplanted cells to be improved. This composition for cell transplant comprises cells and an aqueous solution of a protein (A), and is characterized in that: the cells are myocardial cells and/or cardiac progenitor cells； protein (A) has a hydrophobicity of 0.2-1.2； the protein (A) has a polypeptide chain (Y) and/or a polypeptide chain (Y')； the total number of polypeptide chains (Y) and polypeptide chains (Y') in the protein (A) is 1-100； the polypeptide chain (Y) is an amino acid sequence (X) repeated 2-100 times, the amino acid sequence being any one of a VPGVG sequence (1) which is an amino acid sequence represented by SEQ ID NO:1, a GVGVP sequence (2) which is an amino acid sequence represented by SEQ ID NO:2, a GPP sequence, a GAP sequence, and a GAHGPAGPK sequence (3), which is an amino acid sequence represented by SEQ ID NO:3； the polypeptide chain (Y') is the polypeptide chain (Y) where 0.1-5% of the amino acid residues thereof are substituted with lysine residues and/or arginine residues； and the total number of the lysine residues and arginine residues is 1-100.La présente invention concerne une composition pour transplantation de cellules et un procédé de transplantation de cellules qui permettent à des myocytes et/ou des cellules progénitrices cardiaques d'être convenablement conservés dans du tissu de myocarde et permettent d'améliorer la survie et la prolifération des cellules transplantées. Cette composition pour transplantation de cellules comprend des cellules et une solution aqueuse d'une protéine (A), et est caractérisée en ce que : les cellules sont des cellules de myocarde et/ou des cellules progénitrices cardiaques ； une protéine (A) présente une hydrophobie de 0,2 à 1,2 ； la protéine (A) présente une chaîne polypeptidique
