The present invention addresses the problem of providing a safe and easy-to-prepare cell preparation for prevention and/or treatment of organ fibrosis such as liver fibrosis. Provided is a cell preparation for prevention and/or treatment of organ fibrosis such as liver fibrosis, the cell preparation including a SSEA-3-positive pluripotent stem cell (Muse cell) derived from a vital mesenchymal tissue or a cultured mesenchymal cell.