A biological optical measuring apparatus includes a light source probe and a light receiving probe, one of which is provided with a pressure sensor to detect a contact pressure of a skin of a subject. Pairs of plural values of the contact pressure and light detection signals are previously recorded as calibration data, an estimated value of a false signal is derived from a detection value of the pressure sensor at primary measurement and the calibration data, and a measurement signal waveform in which a noise component due to a movement of the subject is removed is acquired by subtracting the estimated value from a light measurement signal.