To provide a new multi-functional diamine which is a useful monomer having organic groups containing carbon-carbon double bond or carbon-carbon triple bond providing photo-reactivity together with thermal reactivity specific to these reactive groups, and to provide polyimide and polyisoimide comprising the diamine, also to provide methods to produce these.

The diamine is expressed by general formula (1): (wherein R1 represents a univalent organic group containing carbon-carbon double bond or carbon-carbon triple bond, R2 represents hydrogen, a halogen, a methoxy group or an alkyl group having 1 to 20 carbons, R3 represents single bond, -O-, -CH2-, -C(CH3)2-, -S-, -SO2- or-C(CF3)2-, and p is 1 or 0) and characterized in the preparation by the steps of protecting amino groups of a diamine having a hydroxy group with protecting groups, introducing a reactive group and detaching the protecting groups. The polyimide and polyisoimide comprise the diamine.