A pulse wave detecting device, comprising: a) a sensor section in which a plurality of element rows (60, 70) each including a plurality of pressure detecting elements (6a, 7a) arranged in a first direction are arranged in a direction perpendicular to the first direction; b) an air bag that is configured to press the sensor section against a body surface of a living body in a state where the first direction crosses a direction of extending an artery below the body surface; c) a rotation drive section that is configured to rotate the sensor section about each of two axes perpendicular to a pressing direction of the air bag, the two axes being a first axis extending in the first direction and a second axis perpendicular to the first direction; d) a storage control section that is configured to store, in a storage medium, pressure signals detected by the pressure detecting elements (6a, 7a) in a state where a first rotation angle of the sensor section about the first axis is controlled to a first value, a second rotation angle of the sensor section about the second axis is controlled to a second value, and the sensor section is pressed against the body surface by the air bag; and e) a rotation angle determining section that is configured to determine the second value based on the pressure signals detected by the pressure detecting elements (6a, 7a) in a state where the sensor section is pressed against the body surface by the air bag, to perform control of the second rotation angle to the second value by using the rotation drive section, and to determine the first value based on the pressure signals detected by the pressure detecting elements (6a, 7a) with the second rotation angle controlled to the second value, f) wherein the rotation angle determining section is further configured to determine the second value in a state where the sensor section is pressed with a first pressing force, and to determine the first value in a state where the sensor section is pressed with a second pressing force smaller than the first pressing force, and g) a control unit and an air bag drive section, wherein the air bag is configured to be controlled by the control unit via the air bag drive section for adjusting, by a pump, an amount of air held in the air bag, thereby controlling the pressing force applied by the sensor section. a) a sensor section in which a plurality of element rows (60, 70) each including a plurality of pressure detecting elements (6a, 7a) arranged in a first direction are arranged in a direction perpendicular to the first direction; b) an air bag that is configured to press the sensor section against a body surface of a living body in a state where the first direction crosses a direction of extending an artery below the body surface; c) a rotation drive section that is configured to rotate the sensor section about each of two axes perpendicular to a pressing direction of the air bag, the two axes being a first axis extending in the first direction and a second axis perpendicular to the first direction; d) a storage control section that is configured to store, in a storage medium, pressure signals detected by the pressure detecting elements (6a, 7a) in a state where a first rotation angle of the sensor section about the first axis is controlled to a first value, a second rotation angle of the sensor section about the second axis is controlled to a second value, and the sensor section is pressed against the body surface by the air bag; and e) a rotation angle determining section that is configured to determine the second value based on the pressure signals detected by the pressure detecting elements (6a, 7a) in a state where the sensor section is pressed against the body surface by the air bag, to perform control of the second rotation angle to the second value by using the rotation drive section, and to determine the first value based on the pressure signals detected by the pressure detecting elements (6a, 7a) with the second rotation angle controlled to the second value, f) wherein the rotation angle determining section is further configured to determine the second value in a state where the sensor section is pressed with a first pressing force, and to determine the first value in a state where the sensor section is pressed with a second pressing force smaller than the first pressing force, and g) a control unit and an air bag drive section, wherein the air bag is configured to be controlled by the control unit via the air bag drive section for adjusting, by a pump, an amount of air held in the air bag, thereby controlling the pressing force applied by the sensor section.