Objectives: Although radiotherapy is an essential component of pediatric cancer treatment, inadequate radiotherapy information for childhood cancer and unusual treatment situations can negatively affect parental perceptions and emotions. This study aims to investigate the effect of two-step audio-visual instruction system effects introduced by our institution on parent satisfaction and anxiety when initiating radiotherapy. Methods: The two-step audio-visual instruction system comprised instructive animation using patient avatars and a live video system. The live video system has a 55-inch-wide monitor, and a no-latency sound module. Parents in the radiotherapy division can view the patient in the treatment room through the live video system. This prospective study compared satisfaction and anxiety about radiotherapy introduction before and after two-step audio-visual instruction. We enrolled 20 parents whose child underwent radiotherapy, and they completed a set of questionnaires-Client Satisfaction Questionnaire, State-Trait Anxiety Inventory, and original questionnaires about radiotherapy. Results: Satisfaction scores improved significantly after two-step audio visual instruction (25.5 ± 3.4) compared with those before the instruction (27.7 ± 3.1) (p = <0.01). Anxiety scores also decreased significantly after the instruction (50 ± 9) compared with those before the instruction (54 ± 11) (p = 0.004). However, anxiety-related personality trait scores did not change drastically before and after viewing (48 ± 8.5 vs. 49 ± 7.5) (p = 0.419). Conclusion: This single-arm prospective study indicates that two-step audio-visual instruction for radiotherapy is effective in improving parents' anxiety about radiotherapy introductions. However, large-scale and comparative studies are warranted to generalize the benefit of two-step audio visual instruction.