To manufacture an optical wavelength conversion element having a periodic domain inversion structure of an extremely short period.

In this method for manufacturing the optical wavelength conversion element having a periodic domain inversion structure by forming periodic electrodes 13a on one surface 10a of a ferroelectric body 10 which is subjected to monopolarization and has a nonlinear optical effect, then impressing an electric field to the ferroelectric body 10 via these periodic electrodes 13a to form the portions of the ferroelectric body 10 facing the electrodes 13a as local domain inversion parts, a photosensitive resist layer 11 of which only the irradiated portions or non-irradiated portions by photoirradiation are made soluble to a developing solvent, is formed on one surface 10a of the ferroelectric body 10. This resist layer 11 is irradiated with near field light Ln by a means 12 for generating the near field light Ln of the periodic patterns by receiving the light for irradiation. The periodic patterns 11a are formed by developing the resist layer 11 and with these period patterns 11a as a mask, the periodic electrodes 13a are formed on one surface 10a of the ferroelectric body 10 in the opening portions of the mask.