A method for monitoring differentiation into cardiac muscle cells includes keeping, in an alive state, cells into which a reporter gene of luminescent protein configured to vary in luminescence intensity according to an expression of myocardial differentiation marker gene is introduced. The method includes acquiring a luminescence image as a still image by imaging light emitted from the cells in a light shielding state. The method includes acquiring sequential images with illuminating the cells. The method includes associating biological information obtained from the sequential images with biological information obtained from the still image.
