Cloud computing requires broad security solutions based upon many aspects of a large and lightly integrated system. The cloud data storage service releases the users from the burden of huge local data storage and their preservation by out-sourcing mass data to the cloud. One of the significant concerns that need to be spoken is to assure the customer of the integrity i.e. rightness of his data in the cloud. This paper emphasis on the integrity and security of data storage in cloud computing. The data integrity verification is done by introducing Third Party Auditor (TPA) who has privileges to check the integrity of dynamic data in cloud on behalf of cloud client.