The purpose of this paper is to explore ways to cultivate learners who can take part in inquiry, discussion, and action toward realizing an equitable society from the perspective of the SDGs and ESD. After confirming the importance of dealing with the concept of and the issues around equity with consideration of the mutual interdependence among all 17 SDGs, the paper notes that the "inclusive and equitable quality education" mentioned in SDG 4 is assumed to be achieved by the integrated improvement and organization of a variety of aspects, such as educational environment, policy, systems, budget, teachers, and competency development. Next, based on the importance of competency development of all learners through ESD, the paper demonstrates the potentials of objective-referenced assessment for ESD. Finally, the paper proposes a tentative idea on a set of objectives for lessons on equity from the perspective of ESD, as a useful way to develop school-based curricula of quality ESD at each school and to promote effective lessons on equity to prepare learners who can attain the necessary competencies and take part in inquiry, discussion, and action toward realizing an equitable society