to the following embodiment please refer to fig3 to fig6 fig3 shows a portable fingerprint device according to an embodiment of the present invention fig4 illustrates a cross sectional view of the portable fingerprint device fig5 shows another cross sectional view of the portable fingerprint device fig6 illustrates a schematic block diagram of the portable fingerprint device as shown in fig6 a portable fingerprint device 10 which has fingerprint recognition function includes an image sensing unit 101 a microprocessor 102 a signal transmitting unit 103 a memory unit 104 a carrying member 105 and a housing 106 the image sensing unit 101 is used for capturing fingerprint images of a finger in this embodiment the image sensing unit 101 is a capacitance measuring type fingerprint reader the microprocessor 102 is linked to the image sensing unit 101 the microprocessor 102 can record the fingerprint image of the finger identify the fingerprint image of the finger from a fingerprint database receive a command signal and transmit a response signal the signal transmitting unit 103 is connected to the microprocessor 102 and can transmit the command signal and the response signal between the microprocessor 102 and a command device 20 the command device 20 is separated from the portable fingerprint device 10 the connection is presented by a dashed line shown in fig6.