The TG analyses are given for variously meta- and/or para-linked aromatic polyamides with various benzimidazolyl (BI)contents. The TG curves of the polymers were evaluated within 600C by use of an equation for multiple events. The TG curves of BI-substituted polymers are expressed for triple events, though the TG curves of unsubstituted polymer are expressed for double events. The amount of residue of BI-substituted polymers at 800C is larger than that of unsubstituted polymers, perhaps because moieties concerning BI degrade at higher temperatures.