Big data-as-a-Service [BDaaS] platform is used widely to handle and process the large volume of data generated on daily basis from different source. Generated data is usually kept in cloud environment and there may be chances that the system will fail and become subject to numerous forms of assaults. Many researchers have been working to provide security and protection to the data available on cloud. Blockchain technology has emerged as such technology that is used to provide a secured, distributed, and decentralized environment in cloud environment. In this research paper, we are proposing a framework to control the access of data available on big dataas-a-service on cloud platform using blockchain technology as a tool. We are modifying the ciphertext policy- attribute based encryption (CP-ABE) technique and implementing on blockchain platform. Algorithms for all possible situations have been developed using combination of CPABE and blockchain for secured data access in BDaaS. Keywords: Big-Data-as-a-Service [BDaaS], Blockchain, Attribute Based Encryption, Access Control