We investigate the most suitable arrangement of HTS bulks in an active maglev system comprised of multiple HTS bulks and an electromagnet. We measured levitation height and trapped field distribution of a field-cooled bulk as a function of the location of the bulk in the radial direction of the electromagnet. In spite of unstable levitation, the levitation height at the same operating current was increased with the distance between the axes of the bulk and the electromagnet. The levitation force was closely related to the distance among the bulks and the interaction among the bulks was observed when the distance is small. The maximum levitation force was obtained when the bulk was located near the inner boundary of the windings. This implies that the location of multiple bulks realizing the maximum levitation force is closely related to the sizes of electromagnet such as thickness, inner and outer radii and the most suitable arrangement of multiple HTS bulks can be obtained by considering the magnetic field distribution generated by the electromagnet.