PURPOSE: To obtain a novel malondiamide derivative which is useful in the production of organic nonlinear optical elements excellent in transparency and optically functional elements because it has a relatively large nonlinear optical properties as well as high transparency.

CONSTITUTION: This malondiamide derivative is expressed by formula I (Ar1 and A2 are each H, a benzene, naphthalene or anthracene ring substituted with organic substituents), for example, N,N'-bis(4-nitrophenyl)malondiamide of formula II. The compound of formula I is obtained by reaction of a corresponding amino compound of formula III with malonyl chloride of formula IV in the presence of a base. Further, the malondiamide derivative of formula V (Ar3 and Ar4 are each H, benzene, naphthalene, or anthracene substituted with nitro, cyano, isocyanate, carboxy, an alkyl, hydroxyl or phenyl) and a compound of formula VI (Ar is benzene or naphthalene) are novel.