To provide a multi-spectrum illuminometer capable of reducing manufacturing cost, by using a light receiving element which is not an expensive photodiode, instantly measuring even in an environment having weak light such as an undersea environment, and measuring the illuminance at each depth corresponding to a dropping speed of the illuminometer, when measuring undersea light.

Since this multi-spectrum illuminometer has a constitution, wherein since a diffuser 1 for diffusing light is provided and a plurality of light-emitting diodes 2 are provided in parallel corresponding to the diffuser 1, the light is received and uniformized by the diffuser 1; the uniformized light is received by each light-emitting diode 2; bonded electrons are released from bondage to form free electrons by receiving light energy, to thereby generate electromotive force corresponding to light intensity; the illuminance in a prescribed wave range is determined, based on the electromotive force by each light emitting diode 2; and the illuminances from all the light-emitting diodes 2 are used. Hereby, the multi-spectrum illuminance can be acquired, and the multi-spectrum illuminance can be acquired similarly without using the expensive photodiode, and quick measurement can be performed, without requiring the process for storing the light as required in the case of the photodiode.

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