The study of cognitive process is the most important part of the Nyaya Philosophy. It is primarily concerned with the means of acquiring a true cognition of objects. The cognitive process involves in knowing or the act of knowing which in its completeness includes awareness and judgement. According to the Nyaya philosophy, four factors are involved in the cognitive process viz. knower, object of cognition, means of cognition and result of cognition. Out of these the present work focused mainly on Means of Cognition. The scope of the present work is the first ahnika of Nyayamanjari of Jayantabhatta. This work is an attempt to present a critical analysis of the first ahnika of Nyayamanjari and making a comparison with the arguments of opponents which are frequently quoted and refuted by Jayantabhatta. It also presents a critical assessment based on inter school and intra school comparison of key concepts. Thus the aim of this work is to present an in depth study of pramana as a means of valid cognition. So this work is helpful for those readers and researchers who are interested in Indian theory of cognition especially Nyaya theory of cognition.