The residual and inappropriate use of therapeutic drugs goes beyond a clinical problem; it is also an economic problem that causes inefficient allocation of health care resources. Overseas, there have been attempts to examine this influencing factor using traditional health behavior theory. However, those targeting the Japanese population are rare. Furthermore, there is not enough information about the influence of health literacy on the continuous consumption behavior of pharmaceuticals, which has been the focus of much attention in recent years. In this study, we extended the analytical model based on health behavior theory to include health literacy and attempted to reexamine the influence of health literacy on the continuous consumption behavior of pharmaceuticals by path analysis. A total of 1,200 patients, 300 each with a chronic disease (hypertension and diabetes), 300 each with an acute disease (antimicrobials), and 300 each with a need for continuous use of topical medications (glaucoma) were surveyed via the web (no overlap of diseases). Based on previous studies, path analyses were conducted using continuous consumption and intentional/unintentional discontinuation as objective variables and we examined: 1) a full hierarchical model in which all concepts in the health belief model mediate health literacy; 2) a partial hierarchical model in which only self-efficacy mediates health literacy; and 3) a model in which all factor variables are parallel without hierarchy. As a result, model 3, the parallel model, was adopted. The order of influence indicated that addressing unintentional interruptions, such as forgetting to take medication, was given the highest priority, followed by increasing patient self-efficacy, and that consideration should also be given to intentional interruptions, especially in diabetes and glaucoma. On the other hand, health literacy was shown to have a lesser impact than the other concepts.