Eating disorder tendencies are psychological characteristics that are prevalent in healthy young females and are known to be among the risk factors for eating disorders such as anorexia and bulimia nervosa. People with greater eating disorder tendencies strongly associate sweet and fatty foods with weight gain and strictly avoid consuming such foods. However, little is known about how eating disorder tendencies influence the association between taste and body shape impression. Research on crossmodal correspondences suggests that people preferentially associate sweet tastes with round shapes, and individual differences affect the degree of such associations. This study investigates how the degree of taste-shape matching is related to eating disorder tendencies with a preliminary investigation of what mediates this relationship. Two experiments were conducted: in Experiment 1, healthy participants rated the degree of association between basic taste words (sweet/sour/salty/bitter) and roundness of shape and subsequently completed questionnaires addressing eating disorder tendencies. In Experiment 2, participants answered additional questionnaires addressing obsessiveness, dichotomous thinking, and self-esteem. The results of Experiment 1 indicated a positive correlation between drive for thinness, which is one indicator of an eating disorder tendency, and the degree of matching sweetness to round shape. Experiment 2 replicated the results of Experiment 1 and revealed the mediating effect of obsessiveness. These findings suggest a relationship between individual differences in taste-shape matching and eating disorder tendency and the preliminary mediating role of obsessiveness. The present study provides new insight into the role of sweet-round matching in eating disorder tendencies and the associated psychological mechanisms.