PURPOSE: To provide a new N-styrylphthalimide derivative which is useful as an organic nonlinear optical material for producing a wave-changing element.

CONSTITUTION: An N-styrylphthalimide derivative of formula I (X is O, S; at least one of D1 to D4 are each an electron-donating group; at least one of A1 to A5 are each an electron attractive group), for example, N-4'-nitrostyryl-4- dibutylaminophthalimide. The compound of formula I is obtained, for example, by reaction of a compound of formula II with formula III in the presence of cuprous bromide and a trace amount of copper powder at 195°C. In the compounds given by the formula I, the electron-donating groups of D1 to D4 are suitably an alkyl, a dialkyl-substituted amino, alkylthio, or arylthio. The electron attractive groups of A1 to A5 are each a halogen, OH, cyano, nitro, carboxylic acid, acyl ester, sulfonic acid, sulfonic ester or fluoroalkyl.