Toward achieving the Sustainable Development Goals (SDGs) by 2030 adopted at the United Nations Summit in 2015, companies in Japan should be further encouraged regarding these activities. In order to increase the number of companies contributing to the SDGs, a system to check such companies’ progress needs to be developed. Using a constructed comprehensive and quantitative index as a new model for a “certification” system, a questionnaire survey on SDG activities, especially by small and medium-sized enterprises (SMEs) in three advanced companies in Yokohama city, was carried out. Several points in common among the firms, as well as areas for improvement in their SDG efforts were clarified by the results of the questionnaire survey. In addition, the survey content should be improved to ensure that SMEs working on the SDGs are highly evaluated by society. The survey results also indicated that consideration should be given to sustainable management strategies and the feasibility of disseminating information on SDG initiatives outside the company.