A test device includes a housing and a carrier detachable from the housing. The housing includes a socket, and the carrier contains a testing element, and the carrier along with the testing element therein is capable of being inserted into the housing through the socket. The housing includes a blocking structure and a locking structure. The blocking structure and the locking structure are integrated to form a locking component. When the carrier is inserted into the housing, and a position of the carrier is locked by the locking structure, the carrier is abutted against the blocking structure. The carrier keeps stable after being inserted into the housing; and the carrier is located in the same position for each insertion.