Good manufacturing practice (GMP) is advocated and implemented as a standardized procedure for manufacturing dietary supplements. However, in Japan as a case, only half of the manufacturers in this field so far adopt it. To address this issue, the present study aims to explore the effect of key characteristics of a company on the adoption of and compliance with GMP for dietary supplements. The focus is on the effect of expertise in the pharmaceutical industry. The relationships between company characteristics and the adoption of GMP were analyzed for 90 manufacturers in the dietary supplement industry in Japan. A binomial logistic regression analysis showed that each of the following three factors had a positive and significant effect on the company’s adoption of GMP: company size in terms of revenue (odds ratio = 1.04, p = 0.019), possession of a manufacturing license for pharmaceutical products (13.7, p = 0.003), and number of own product categories manufactured (3.93, p = 0.00009). These findings strongly suggest that the company’s manufacturing capability of pharmaceutical products works as a key driver for the better adoption of a quality standard in the dietary supplement industry in Japan. Few considerations were made for conditions of the adoption and implementation of GMP. The present study empirically contributes by providing key clues for issues in the dietary supplement industry and by forming a theoretical base for policymakers and the regulatory authorities.