PROBLEM TO BE SOLVED: To provide a high quality cell culture without comprising impurity components derived from a production process which may become an obstacle to clinical application, and a production method of the same.SOLUTION: The invention relates to: a production method of a sheet-like cell culture comprising (i) a step of inoculating cells onto a culture substrate coated with serum and (ii) a step of culturing the cells to form a sheet-like cell culture； a sheet-like cell culture produced by the method； a culture substrate coated with serum for use in the method； a production method of the culture substrate and a production kit thereof； and a method to suppress inflammatory cytokine production in cell culture comprising (i) a step of inoculating cells onto a culture substrate coated with serum, and (ii) a step of culturing the cells with serum free medium to form a cell culture.
