A biometric data detection device (12,62) adapted to be connected to a data processing terminal, the biometric data detection device (12, 62,) comprising: a biometric authentication sensor adapted to be electrically connected to the data processing terminal through a connecting member; a housing that houses the biometric authentication sensor; wherein the housing is a substantially rectangular box shaped member, comprising four corner portions as viewed along a direction normal to the housing, a window portion that acquires biometric data to be authenticated by the biometric authentication sensor, and that is formed in the housing; an attachment member that is rotatably provided at the housing, and that renders the housing rotatable in a state in which the housing is attached to the data processing terminal; wherein the attachment member includes a rotating body, and a universal serial, USB, plug, and the rotating body is rotatable with respect to the housing about a center line and one of the four corner points is a non-contact portion that is formed at the housing, and that is located between: a first edge that is formed at the housing, and that when connected by way of the USB plug to the terminal is configured to face the data processing terminal at a first orientation (SS-1) of the housing, and a second edge that is formed at the housing, and that is adjacent to the first edge and that, when connected to the terminal by way of the USB plug, is configured to face the data processing terminal at a second orientation (SS-2) that has been rotated from the first orientation, wherein the non-contact portion is a shorter distance from said center line than the first edge and the second edge. a biometric authentication sensor adapted to be electrically connected to the data processing terminal through a connecting member; a housing that houses the biometric authentication sensor; wherein the housing is a substantially rectangular box shaped member, comprising four corner portions as viewed along a direction normal to the housing, a window portion that acquires biometric data to be authenticated by the biometric authentication sensor, and that is formed in the housing; an attachment member that is rotatably provided at the housing, and that renders the housing rotatable in a state in which the housing is attached to the data processing terminal; wherein the attachment member includes a rotating body, and a universal serial, USB, plug, and the rotating body is rotatable with respect to the housing about a center line and one of the four corner points is a non-contact portion that is formed at the housing, and that is located between: a first edge that is formed at the housing, and that when connected by way of the USB plug to the terminal is configured to face the data processing terminal at a first orientation (SS-1) of the housing, and a second edge that is formed at the housing, and that is adjacent to the first edge and that, when connected to the terminal by way of the USB plug, is configured to face the data processing terminal at a second orientation (SS-2) that has been rotated from the first orientation, wherein the non-contact portion is a shorter distance from said center line than the first edge and the second edge. a first edge that is formed at the housing, and that when connected by way of the USB plug to the terminal is configured to face the data processing terminal at a first orientation (SS-1) of the housing, and a second edge that is formed at the housing, and that is adjacent to the first edge and that, when connected to the terminal by way of the USB plug, is configured to face the data processing terminal at a second orientation (SS-2) that has been rotated from the first orientation, wherein the non-contact portion is a shorter distance from said center line than the first edge and the second edge.