There is no legal requirement that you have prior experience in order to purchase a business, but a good working knowledge of the business and its industry can contribute substantially to your success.
However, in practice, experience is often required. If there is a degree or license involved (ex: a dental practice), a Seller may expect substantial prior experience before even considering your offer. Landlords usually require appropriate experience before they will approve a Buyer’s tenancy, and lenders routinely require prior experience to approve financing.
Each opportunity has its own unique set of requirements, so experience requirements should be evaluated on a case-by-case basis.