In the exploitation of magnetic robot hands, it is extremely important to develop a gap sensor with high and stable performance for the relative motion in three-dimensional space between the held body and the magnetic robot hand. In this study, first, a prototype gap sensor system is developed for the instrument of the gap between a magnetic robot hand and a spherical magnetic body held and transferred without contact. The prototype gap sensor system consists of a magnetic flux sensor, an exciting current sensor and a data base calculation system. The data base calculation system is constructed using instrument data obtained in previous experiments for the gap, the magnetic flux and the exciting current. The magnetic robot hand is composed of a prototype gap sensor system and an electromagnet. Second, experiments on the noncontact hold and transfer control of the spherical magnetic body are carried out and it is confirmed that the spherical magnetic body can be held and transferred successfully without contact between the magnetic robot hand and the prototype gap sensor system.