As a citizen of India we have to know about our Constitution. Because it is the supreme law of our nation. Not only Indian citizens but also the citizens of another country who are known as foreigners they also want to know about the constitution of India. Because the Constitution of India is the lengthiest written constitution of the world though the Indian constitution is not so old. Being the broadest written constitution of the world it is not easy to take idea about the Indian constitution in a very short time. The Preamble of the Indian constitution helps to take ideas about the subject matter of the Indian constitution very easily in a very short time. For this reason the preamble of the Indian constitution is known as the mirror of the constitution of India. In this article I focus on that why preamble is so important and it plays what types role as a mirror.