Internet is a place where people stores and shares information among the other entities reside in the network. In recent years, the amazing development of web technologies, lead to huge quantity of system and user generated information in online systems. This huge amount of information on web platforms enables them to use as data sources, in review making applications based on opinion mining and sentiment analysis. The paper put forward an algorithm for detecting sentiments on user reviews on movie, based on Naive Bayes classifier. We considered the opinion mining domain for the analysis of user reviews and the techniques used in sentimental analysis. We implemented the proposed algorithm to the user reviews and tested its performance, and suggested directions of development. © 2016, Institute of Integrative Omics and Applied Biotechnology. All rights reserved.