An apparatus for measuring bio-information, the apparatus comprising: a heart rate sensor unit configured to measure heart rates by receiving a light that has entered and come out from skin; an acceleration sensor unit configured to output a step count by measuring the step count of a wearer; a display unit configured to display the measured heart rates and step count; and a wrist-wearable connection unit configured to electrically connect the heart rate sensor, the acceleration sensor unit and the display unit, characterized in that the heart rate sensor unit includes a line light source unit, a light receiving unit (120,130,140,150) configured to receive the light that has entered and come out from the skin from the light emitted from the light source unit, and a controller configured to detect the heart rates from a quantity of light received by the light receiving unit, wherein the light receiving unit (120,130,140,150) includes a first light receiving unit arranged at an upper left surface based on a lengthwise direction of the light source unit, a second light receiving unit arranged at an upper right surface based on a lengthwise direction of the light source unit, a third light receiving unit arranged at a bottom left surface based on a lengthwise direction of the light source unit, and a fourth light receiving unit arranged at a bottom right surface based on a lengthwise direction of the light source unit, further characterized in that the heart rate sensor unit is configured to detect an error by comparing light signals received by the first to fourth light receiving units (120,130,140,150), multiply a predetermined weight to a greater light signal as a result of comparison of the light signals when the error is generated, and add a size of a light signal multiplied by the weight to a size of a light signal not multiplied by the weight. a heart rate sensor unit configured to measure heart rates by receiving a light that has entered and come out from skin; an acceleration sensor unit configured to output a step count by measuring the step count of a wearer; a display unit configured to display the measured heart rates and step count; and a wrist-wearable connection unit configured to electrically connect the heart rate sensor, the acceleration sensor unit and the display unit, characterized in that the heart rate sensor unit includes a line light source unit, a light receiving unit (120,130,140,150) configured to receive the light that has entered and come out from the skin from the light emitted from the light source unit, and a controller configured to detect the heart rates from a quantity of light received by the light receiving unit, wherein the light receiving unit (120,130,140,150) includes a first light receiving unit arranged at an upper left surface based on a lengthwise direction of the light source unit, a second light receiving unit arranged at an upper right surface based on a lengthwise direction of the light source unit, a third light receiving unit arranged at a bottom left surface based on a lengthwise direction of the light source unit, and a fourth light receiving unit arranged at a bottom right surface based on a lengthwise direction of the light source unit, further characterized in that the heart rate sensor unit is configured to detect an error by comparing light signals received by the first to fourth light receiving units (120,130,140,150), multiply a predetermined weight to a greater light signal as a result of comparison of the light signals when the error is generated, and add a size of a light signal multiplied by the weight to a size of a light signal not multiplied by the weight.