A biological information acquiring device for measuring biological information of a subject with a pressure sensor, the device comprising: one or a plurality of multi-axis pressure sensors for detecting pressure in directions along two or more axes intersecting at a predetermined angle, each of the multi-axis pressure sensors including a signal detection means for detecting a signal of a pressure component for each axis of a pulse wave of the subject; an arithmetic unit for calculating outputs of the multi-axis pressure sensors, the arithmetic unit including a pulse waveform synthesizing means for synthesizing a pulse waveform based on the signals of the pressure components for respective axes detected by the multi-axis pressure sensors; a sensor position moving mechanism (14, 15) for adjusting a position of the multi-axis pressure sensors with respect to the subject, and a controller for controlling the sensor position moving mechanism (14, 15) on the basis of the outputs of the multi-axis pressure sensors to move the sensors to a more accurate pulse wave measurement position; the sensor position moving mechanism (14, 15) including actuators for moving the multi-axis pressure sensor in the directions along at least an X axis and a Z axis and for changing an α angle with respect to a blood vessel of the living body subjected to measurement by the multi-axis pressure sensor, where the Z axis corresponds to the direction in which the blood vessel pushes a surface of the skin of the subject, the X axis corresponds to the direction perpendicular to an axial direction of the blood vessel and orthogonal to the Z axis, a Y axis corresponds to the axial direction of the blood vessel, the α angle is an inclination of the multi-axis pressure sensor about an X-Z axes plane, and a β angle is the inclination of the multi-axis pressure sensor about a Z-Y axes plane, wherein, the controller is configured to use triaxial outputs of the multi-axis pressure sensors and the arithmetic unit is configured to use a single axis output from the multi-axis pressure sensors. one or a plurality of multi-axis pressure sensors for detecting pressure in directions along two or more axes intersecting at a predetermined angle, each of the multi-axis pressure sensors including a signal detection means for detecting a signal of a pressure component for each axis of a pulse wave of the subject; an arithmetic unit for calculating outputs of the multi-axis pressure sensors, the arithmetic unit including a pulse waveform synthesizing means for synthesizing a pulse waveform based on the signals of the pressure components for respective axes detected by the multi-axis pressure sensors; a sensor position moving mechanism (14, 15) for adjusting a position of the multi-axis pressure sensors with respect to the subject, and a controller for controlling the sensor position moving mechanism (14, 15) on the basis of the outputs of the multi-axis pressure sensors to move the sensors to a more accurate pulse wave measurement position; the sensor position moving mechanism (14, 15) including actuators for moving the multi-axis pressure sensor in the directions along at least an X axis and a Z axis and for changing an α angle with respect to a blood vessel of the living body subjected to measurement by the multi-axis pressure sensor, where the Z axis corresponds to the direction in which the blood vessel pushes a surface of the skin of the subject, the X axis corresponds to the direction perpendicular to an axial direction of the blood vessel and orthogonal to the Z axis, a Y axis corresponds to the axial direction of the blood vessel, the α angle is an inclination of the multi-axis pressure sensor about an X-Z axes plane, and a β angle is the inclination of the multi-axis pressure sensor about a Z-Y axes plane, wherein, the controller is configured to use triaxial outputs of the multi-axis pressure sensors and the arithmetic unit is configured to use a single axis output from the multi-axis pressure sensors.