A measuring tape device has a hook piece. The hook piece is used for preventing the tape from slipping off from an object of measure. The hook piece consists of a hook body and an anti-slip piece; the hook body consists of a pulling part and a connecting part; the pulling part is a flat surface, the connecting part extends out from one side of the pulling part in the direction that is perpendicular to the pulling part; the anti-slip piece is adhered onto the inside surface of the pulling part; and magnetic pieces are attached to the outside surface of the pulling part. Therefore, during the measuring process, both the anti-slip piece and the magnetic pieces may help keeping the hook plate of the measuring tape attaching to the object of measure and hence the tape does not slip off from the object of measure easily.