Novel polyimides substituted by a substituent having an alkyl or fluoroalkyl group and having reduced water absorption; a process for producing these novel polyimides; and novel acid dianhydrides to be used in the production thereof. A polyimide containing a structure represented by the following general formula (I): ##STR1## wherein X.sup.1 represents a tetravalent organic group having a substituent --R.sup.1 AR.sup.2 (wherein A represents a divalent linkage group; R.sup.1 represents a single bond or a C.sub.1-3 alkylene group; and R.sup.2 represents a C.sub.1-25 alkyl group or a fluoroalkyl group); and Y represents a divalent organic group.
