A terminal device comprising: a physiological signal measurement unit comprising a battery cover covering an area where a battery of the terminal device is detachably attached and a sensor configured to detect a physiological signal, the sensor being included in the battery cover; a communication unit configured to transceive data with the physiological signal measurement unit; a control unit configured to control a display to display information about a detected physiological signal; and the display configured to display the information about the detected physiological signal, wherein the physiological signal measurement unit is detachably attached to the terminal device as the battery cover is detachably attached to the terminal device, wherein the physiological signal measurement unit is configured to generate physiological contact state information including an area where a physiological contact is detected as the sensor measuring a physiological signal detects the physiological contact, the communication unit is configured to receive the generated physiological contact state information, the display is configured to display the received physiological contact state information, and the control unit or the physiological signal measurement unit is configured to determine whether the physiological signal is measurable based on the physiological contact state information, wherein the terminal device further comprises an output unit configured to output a result of the determination via a sound signal or a vibration signal, wherein the terminal device is configured to output the result of the determination via the display or the output unit, and wherein, when the physiological signal is measurable, the physiological signal measurement unit is configured to measure a physiological signal and transmit a result of the measurement to the control unit, and the control unit is configured to control the display to display the measured physiological signal; and wherein the display is a touch screen configured to detect an input in a predetermined area of the display, and as the touch screen detects an input in the predetermined area of the display, the control unit is configured to control the physiological signal measurement unit to detect the physiological contact; and wherein the control unit is configured to control the display to display an object indicating a position of the sensor included in the battery cover, where the object is positioned on the display to perpendicularly match a position of the sensor in the battery cover. a physiological signal measurement unit comprising a battery cover covering an area where a battery of the terminal device is detachably attached and a sensor configured to detect a physiological signal, the sensor being included in the battery cover; a communication unit configured to transceive data with the physiological signal measurement unit; a control unit configured to control a display to display information about a detected physiological signal; and the display configured to display the information about the detected physiological signal, wherein the physiological signal measurement unit is detachably attached to the terminal device as the battery cover is detachably attached to the terminal device, wherein the physiological signal measurement unit is configured to generate physiological contact state information including an area where a physiological contact is detected as the sensor measuring a physiological signal detects the physiological contact, the communication unit is configured to receive the generated physiological contact state information, the display is configured to display the received physiological contact state information, and the control unit or the physiological signal measurement unit is configured to determine whether the physiological signal is measurable based on the physiological contact state information, wherein the terminal device further comprises an output unit configured to output a result of the determination via a sound signal or a vibration signal, wherein the terminal device is configured to output the result of the determination via the display or the output unit, and wherein, when the physiological signal is measurable, the physiological signal measurement unit is configured to measure a physiological signal and transmit a result of the measurement to the control unit, and the control unit is configured to control the display to display the measured physiological signal; and wherein the display is a touch screen configured to detect an input in a predetermined area of the display, and as the touch screen detects an input in the predetermined area of the display, the control unit is configured to control the physiological signal measurement unit to detect the physiological contact; and wherein the control unit is configured to control the display to display an object indicating a position of the sensor included in the battery cover, where the object is positioned on the display to perpendicularly match a position of the sensor in the battery cover.