A biosignal measurement apparatus including: a bracelet membrane to wear around a user's wrist; a fixing supporter to install in a first side portion of the bracelet membrane and to support a first side portion of the wrist; a moving supporter to install in a second side portion of the bracelet membrane, to move towards the fixing supporter, and closely to attach to a second side portion of the wrist; and an information control unit to calculate a distance between the first side portion of the wrist and the second side portion of the wrist by detecting a movement distance of the moving supporter, and to calculate a displacement of the radial artery of the wrist by using a predetermined constant and the calculated distance between the first side portion of the wrist and the second side portion of the wrist.