Mortgage contract is subordinate to contract. A mortgage contract is a guarantee contract signed by the mortgagee (usually the creditor) and the mortgagor (either the debtor or the third party). The mortgagor sets mortgage guarantee to the mortgagee with certain property (including real estate and movable property). When the debtor fails to perform the debt, the mortgagee can get priority compensation from the price obtained from the disposal of the collateral according to law. Mortgage contracts include known contracts, agreed contracts, unilateral contracts, free contracts, necessary contracts, definitive contracts and subordinate contracts. According to the master-slave relationship between contracts, contracts can be divided into master contracts and slave contracts. The so-called accessory contract is a contract based on the existence of other contracts. Because the subordinate contract depends on the existence of the main contract, it is also called "subsidiary contract". Such as guarantee contract, mortgage contract, etc. They are all subordinate contracts relative to the main debt contract. Without the main debt, there can be no guarantee of the main debt, and there is no guarantee contract, so the mortgage contract must be a subordinate contract.