Internet of Things (IoT) is now making a new industrial revolution, which includes "Industrie4.0" in Germany, "Industrial Internet" in US, "Made in China 2025" in China, and the "Industrial Value Chain Initiative (IVI)" in Japan. In the modern global, competitive, and collaborative business environment, IoT services must be designed as a business ecosystem. Although many business-model design methods, including our own design method presented in PICMET2015, have been proposed, there exist few business-ecosystem design methods that target IoT services especially. Here, a business-ecosystem design method is proposed for loT services using an "Open & Closed Strategy Canvas," on which designers can recognize both a closed area, where the company keeps and strengthens their core competence, and an open area, where complementary companies provide resources (knowledge resource, manufacturing resource, and deployment resource) to the business ecosystem.