Atayal is one of the Austronesian languages spoken in Taiwan. It consists of two major subgroups, namely, Squliq and C’uli’. The present paper attempts to provide a description of the case marking system (including pre-nominal case markers and the nominal case marking suffix) of Plngawan Atayal, a C’uli’ dialect spoken in Jen-ai Prefecture, Nantou County. Its population is around 1000, with less than one-third of the people being able to speak the dialect. The case markers of Plngawan Atayal will be examined in terms of their morphological forms, syntactic distribution, and syntactic/semantic functions. Furthermore, a brief comparison of the case marking systems of Wulai Atayal (Squliq), Mayrinax Atayal (C’uli’) and Plngawan Atayal will be presented.