The questionnaire will be used to collect primary data to reliably analyse the huge number of people because it is a common way to collect a large number of data. (Saunders et al, 2016). Also, Bill (2006) states that collecting questionnaire is a quick way to gather data with low financial cost. However, the questionnaire could not contain important point so it might have a gap in crucial information. According to Hair Jr, Wolfinbarger, & Money (2015), the good questionnaire leads to effective data in order to generate a good result of research. Consequently, this study will find the correlation between a factor of e-WOM and customer behaviour in Thailand. Certainly, the study requires a large number of data to gather reliable analysis. As a result, it seems that survey is suitable for this study.