To achieve autonomous cooperation among heterogeneous agents, we propose the artificial minimal self. The artificial minimal self is implemented based on the free energy principle (FEP), which all living organisms are supposed to follow. In a standard FEP, the generative model configured for each physical agent consists only of its own observations and actions. The key to autonomous cooperation among heterogeneous agents is to extend the sense of self beyond to others to include interaction with others to self. In this study, focusing on Gallagher’s minimal self where the self is extended to others, the generative model integrates its own observations and actions and those of other heterogeneous agents. Multiple heterogeneous physical agents have different embodiments, resulting in different types of observations and actions. To integrate different types of observations and actions, we define observations and actions based on environmental information independent of the agent’s embodiment. Integrating the observations and actions of multiple physical agents into a generative model allows extending the sense of self beyond to others, leading to autonomous cooperation between heterogeneous agents. We demonstrated cooperative object transport by two heterogeneous robot arms implementing the artificial minimal self. The results confirmed that each robot arm can autonomously share tasks and transport objects by simply providing a common goal of placing the object into the goal. Furthermore, the process of self-extension to others reproduced the behavior of observing the characteristics of others that is seen in human cooperation.