The emotional response of users induced by VR scenarios has become a topic of interest, however, whether changing the size of objects in VR scenes induces different levels of anxiety remains a question to be studied. In this study, we conducted an experiment to initially reveal how the size of a large object in a VR environment affects changes in participants' (N = 38) anxiety level and heart rate. To holistically quantify the size of large objects in the VR visual field, we used the omnidirectional field of view occupancy (OFVO) criterion for the first time to represent the dimension of the object in the participant's entire field of view. The results showed that the participants' heartbeat and anxiety while viewing the large objects were positively and significantly correlated to OFVO. These study reveals that the increase of object size in VR environments is accompanied by a higher degree of user's anxiety.