Professor Tenna designs a robot in the likeness of his young son, tragically killed in an automobile accident. Disappointed in the robot child's inability to nurture and grow, he sells it to a robot circus.

Christened Astro Boy, he quickly becomes a public spectacle, experiencing humiliation and distress in the process. In the midst of his despair, a sympathetic professor at the circus seeking to save the boy robot from his plight, takes Astro Boy under his wing, educating him and introducing a robot family to his life.

With a new, strong sense of self, Astro Boy overcomes contradictions and discrimination in human society by fighting for justice and peace for mankind.