PROBLEM TO BE SOLVED: To provide a new method for the diagnosis of the growth of a plant based on indices and analysis capable of more clearly and widely showing diagnostic result of the growth of plant while solving the problems of the conventional growth diagnosis using second order differentiation method such as a large number of evaluation factors necessary for the diagnosis. SOLUTION: The growth of a plant is diagnosed by irradiating the leaf of the plant with a laser beam, measuring the intensity of the generated fluorescence, making a graph of the variation of the fluorescent intensity with time, integrating the fluorescent intensity on the graph and comparing the result with preparatorily determined standard values comprising the normal activation value (NV) and the limit growth value (LB).
