To provide a wavelength converter which is usable in wide wavelengths and in which a light emission wavelength can be designed easily and whose cost is low because of its simple structure and which is capable of being miniaturized.

This device has a first optical transmission line 1 through which light is guided and transmitted and the wavelength of the light transmitted from the first optical transmission line 1 is converted and transmitted to a second optical transmission line 4. Moreover, the device is provided with an electron emitting part 2 which is provided with an electron emitter 22 which is connected optically to the first optical transmission line 1 and is excited by the light transmitted from the first optical transmission line 1 to emit electrons and a light emitting body 3 which is connected optically to the second optical transmission line 4 and is excited by the electrons emitted from the electron emitter 22 of the electron emitting part 2 to generate light having a wavelength different from that in the first optical transmission line 1.