The theory of anātman was found, proved and preached by Gautama Buddha. It was established to fight against the Brahma thought gathered in Upaniads. However, some scholars considered the anātman theory of Buddha never mentioned the mistakes of the metaphysical Brahma, nor the ātman as a subject of the transmigration. They thought the only reason why Buddha pointed out the anātman theory is to getting rid of all defilements toward Ego by practicing meditation. They even considered the anātman theory is nothing to do with those basic principles preached by Buddha: five aggregates, cause and effect, mergence theory. They thought anātman theory combined with these basic principles of Buddhism was organized by followers of Buddha, not Buddha himself. Some researches of these scholars showed the mergence theory of Buddha was borrowed from Jainism. In order to refute these heretical opinions, this thesis discusses as follow: From the beginning, this thesis tries to discuss the basic meanings of Brahma by three steps: First, by discussing five poems of the Rg-Veda to discover how the world was built. After that and according to that, Prajapati, Brahman and ātman were developed in Brahmana. Finally, the theory of “Brahma is identical to ātman” was coming out in Upaniads. Basic on that, this thesis discusses the cause and effect law that preached by Buddha. Buddha considered that the five aggregates of mankind are impermanence and following the cause and effect law. He did not think there is permanence existence in or out or co-exist with five aggregates. From these discussing above, we could see clearly that the aim of anātman theory of Buddha was built surely to fight against the Brahma and the ātman thought at that time. The last part of the thesis is explaining the “anātman theory of five aggregates” is identical to “anātman theory of cause and effect” by making comparisons on some articles of Dhamma-pada and Āgamas to refute the opinions held by those scholars vi who think that the anātman theory is unrelated to the cause and effect law, the five aggregates or the mergence theory.