To provide a plant wavelength sensor device that is applicable to various growth parameters of the target plant. A plant wavelength sensor device (10) includes a light emission portion (21) for emitting a measurement light P to irradiate a target plant (Cr), a light receiving portion (22) for receiving the measurement light (P) reflected on the target plant as a reflected light (Pr); and a control section (23, 24, 25) for controlling the light emission portion and the light receiving portion. The control section is configured to emit the measurement light (P) having a wavelength range corresponding to a selected growth parameter (Eg) from the light emission portion, to receive the reflected light (Pr) from the target plant with the light receiving portion with respect to the measurement light (P) having the wavelength range corresponding to the selected growth parameter (Eg), and to calculate a volume of the reflected light from the target plant as a reflected light volume with respect to the wavelength range
