The soluble polyimides were synthesized from tetracarboxylic dianhydrides such as 3,4'-oxydiphthalic anhydride (3,4'-ODPA) and diamine monomers having various functional groups such as long-chain alkyl groups, natural products, unsaturated long-chain alkyl group, t-Boc or o-nitrobenzyl group. The thin films of obtained polyimides were irradiated by UV light (λmax; 254 nm or 365 nm), and the contact angles for the water decreased from near 100^o (hydrophobicity) to minimum 20^o (hydrophilicity) in proportion to irradiated UV light energy. From the result of contact angle measurements and the result of the ATR and XPS analysis, it is recognized that the hydrophobic groups on the polyimide surface decrease and the hydrophilic groups such as carboxyl groups and hydroxyl groups generate on their surface. Thus, the surface wettability of these polyimides can be controlled by UV light irradiation.