Securing and managing medical data in hospitals is one of the significant challenges still existing in healthcare. There can be different kinds of patients staying in hospitals with various diseases. All these medical data records need to be secured appropriately for future use and verification. In the hospital, there will be essential documents such as criminal cases and postmortem reports, although it is unclear if they are being handled properly or not. Even the hospital staff can alter these data. This paper proposes a blockchain-based secured medical data management system to manage access to each medical record in a network of hospitals. The proposed system has three main access management categories: one for securing general (fever or cold) medical report, category 2 for postmortem or crime reports security and category 3 for securing cancer /brain death /genetic disorder reports. Sensitive clinical data should not be visible to patients with cancer or genetic disorders as these patients have a higher rate of suicide attempts. Hence, the data is accessible only to doctors, family members, and researchers. The data related to the crime or postmortem reports have only limited access for those with legal permission to access and verify these types of reports. So through blockchain distributed ledger technology and smart contracts, we could store the data in a tamper-proof manner and manage the user access to these data.