A biometric information detecting device (100, FS) comprising: a measurer measuring biometric information of a user as an electrical signal; a determiner (20, 25, 28) connected to the measurer to receive the electrical signal, processing the electrical signal according to a first reference condition to output a first result signal, and processing the electrical signal according to a second reference condition to output a second result signal, the second reference condition being different from the first reference condition; a controller controlling the determiner (20, 25, 28) to determine whether the electrical signal corresponds to a ridge or a valley using a first and a second reference range (RA1, RA2) such that the determiner (20, 25, 28) is operated in the first reference condition and in the second reference condition; and a processor processing the first and second result signals (RS1, RS2) to obtain the biometric information of the user, wherein the determiner (20, 25, 28) comprises an analog-to-digital converter (22, 23, 24, 27) that converts the electrical signal in an analog form to a digital signal based on the first reference range to output the first result signal and converts the electrical signal in an analog form to a digital signal based on the second reference range to output the second result signal, wherein the processor comprises: a synthesizer synthesizing the first result signal and the second result signal to output a final result signal; and an imaging processor processing the final result signal to obtain the biometric information of the user, wherein the synthesizer applies both the first and second result signals (RS 1, RS2) and generates the final result signal from the first and second result signals (RS 1, RS2) characterized in that the first reference range is defined between a first reference voltage (Vref1) and a second reference voltage (Vref2), the second reference range is defined between a third reference voltage (Vref3) and a fourth reference voltage (Vref4), and the second reference range is included in the first reference range, and the synthesizer applies different weights to the first and second result signals (RS 1, RS2) and sums the first and second result signals (RS 1, RS2) to generate the final result signal. a measurer measuring biometric information of a user as an electrical signal; a determiner (20, 25, 28) connected to the measurer to receive the electrical signal, processing the electrical signal according to a first reference condition to output a first result signal, and processing the electrical signal according to a second reference condition to output a second result signal, the second reference condition being different from the first reference condition; a controller controlling the determiner (20, 25, 28) to determine whether the electrical signal corresponds to a ridge or a valley using a first and a second reference range (RA1, RA2) such that the determiner (20, 25, 28) is operated in the first reference condition and in the second reference condition; and a processor processing the first and second result signals (RS1, RS2) to obtain the biometric information of the user, wherein the determiner (20, 25, 28) comprises an analog-to-digital converter (22, 23, 24, 27) that converts the electrical signal in an analog form to a digital signal based on the first reference range to output the first result signal and converts the electrical signal in an analog form to a digital signal based on the second reference range to output the second result signal, wherein the processor comprises: a synthesizer synthesizing the first result signal and the second result signal to output a final result signal; and an imaging processor processing the final result signal to obtain the biometric information of the user, wherein the synthesizer applies both the first and second result signals (RS 1, RS2) and generates the final result signal from the first and second result signals (RS 1, RS2) characterized in that the first reference range is defined between a first reference voltage (Vref1) and a second reference voltage (Vref2), the second reference range is defined between a third reference voltage (Vref3) and a fourth reference voltage (Vref4), and the second reference range is included in the first reference range, and the synthesizer applies different weights to the first and second result signals (RS 1, RS2) and sums the first and second result signals (RS 1, RS2) to generate the final result signal. a synthesizer synthesizing the first result signal and the second result signal to output a final result signal; and an imaging processor processing the final result signal to obtain the biometric information of the user, wherein the synthesizer applies both the first and second result signals (RS 1, RS2) and generates the final result signal from the first and second result signals (RS 1, RS2) characterized in that the first reference range is defined between a first reference voltage (Vref1) and a second reference voltage (Vref2), the second reference range is defined between a third reference voltage (Vref3) and a fourth reference voltage (Vref4), and the second reference range is included in the first reference range, and the synthesizer applies different weights to the first and second result signals (RS 1, RS2) and sums the first and second result signals (RS 1, RS2) to generate the final result signal.