Testing plays an important role in the maintenance of Component Based Software Development. Test adequacy for component testing is one of the hardest issues for component testing. To tackle this problem, it is a natural idea to apply mutation testing, which is a fault-based testing method used for measuring test adequacy, for component contracts, whose aim is to improve the testability of the component. Though powerful, mutation testing is usually very computation-expensive, as many mutants need to be produced and executed in mutation testing. In this paper, we propose a contract-based mutation technique for testing components. Based on the discordance between contracts and specification, our approach employs a set of high level contract mutation operators. The experimental results show that these operators can greatly reduce the number of mutants compared with traditional mutation operators. At the same time, the contract-based mutation using our contract mutation operators can provide almost the same ability as that of using traditional mutation operators. Moreover, effective test suite can be produced to reduce the maintenance effort.