As a forecasting tool, audience movie reviews provide a guide for film companies. This study uses a text mining technique to analyze the American film market. It explores movie reviews including word of mouth (WOM) factors (i.e., movie content, positive, negative, and promotion) and related factors (i.e., time, rating, and the number of ratings) for the box office. According to the relationship between the keyword clusters, the major factors that affect the box office are determined. The findings provide reference for movie producers to manipulate WOMs.