Color carries gender information (e.g., red–female/blue–male). This study explored whether red could bias sex categorization of human bodies. Visual stimuli were created from body silhouettes that varied along the waist-to-hip ratio from female to male perception, combined with the red, green, and gray colors that were used as body color (Exp. 1) and background color (Exp. 2). Participants were instructed to categorize the sex of body stimulus as male or female by pressing one of two labelled keys. Results showed that red body color induced a female-body bias, while red background color induced a male-body bias, compared with green and gray colors. Thus, red plays a role in body-sex processing, and the color positioning affects this red effect. Those results suggest that there are different levels of activation of color–sex associations in the body-sex perception.