We propose a VR-based learning support system focused on not only experience but also collaborative learning. We try to enhance understanding of "balance of force" in the elementary dynamics. The virtual laboratory in the system is shared by two or more students, and invisible information such as size and direction of a force applied by each student is shown in the virtual laboratory. Furthermore, each student can also feel a sense of force using a force feedback device. This paper describes the system concept and the system outline, and then discusses the possibility of the collaborative learning through the developed system.