Embodiments of the invention provide a data storage device test method and data storage device manufacture method which allow a tester to perform an operation test of plural data storage devices connected thereto in a shorter period of time. In one embodiment, an operation test of each of plural HDDs 81-84 connected to a tester is performed by making plural HDDs 81-84 execute commands received from the tester, wherein, during a waiting period when exchange stops between the tester and, for example, HDD 81 of which operation test is being executed, the tester executes the operation test of another HDD. Such a waiting period occurs, for example, before HDD 81 becomes ready to receive a command, before a data transfer is completed and before HDD 81 becomes ready to receive the subsequent command. By using this waiting period, the tester issues a command to, for example, HDD 82 if the HDD is ready to receive a command or transfers data to the HDD if data transfer is possible.