An image wavelength conversion device for converting an infrared light image into a visible light, a method of manufacturing the device, and an image conversion system using the device are provided. The image wavelength conversion device is formed by an optical waveguide array 3 in which one end and the other end of each of a multitude of quasi-phase-matching sum frequency generating optical waveguides are aligned in a two-dimensional plane. One plane of the optical waveguide array 3 forms an incident plane which includes respective waveguides as elements thereof, and the other plane of the optical waveguide array 3 forms an exit plane which includes waveguides corresponding to the waveguides of the incident plane as elements thereof. From an incident light (.lamda..sub.1) and an excitation light (.lamda..sub.2) incident to an arbitrary element of the incident plane, an output light (.lamda..sub.3) having the relationship of (.lamda..sub.1).sup.-1+(.lamda..sub.2).sup.-1=(.lamda..sub.3).sup.-1 is generated in the corresponding waveguide element. .lamda..sub.1, .lamda..sub.2, and .lamda..sub.3 here represent the wavelength of the incident light, the wavelength of the excitation light, and the wavelength of the output light, respectively.