A surface property measuring apparatus comprising: a roughness measuring instrument configured to measure a surface property of a measured surface of a measured object by tracing the measured surface while being kept in contact with the measured surface, the roughness measuring instrument including: a measuring arm supported so as to make an arc-like movement about a rotating shaft as a fulcrum; a stylus (233U, 233D) provided at a distal end of the measuring arm; a displacement detector configured to detect a displacement of the measuring arm which occurs as a result of the measuring arm having made an arc-like movement; and a measuring force application unit configured to bias the measuring arm in a direction in which the measuring arm makes an arc-like movement to thereby apply a measuring force to the stylus (233U, 233D); a relative moving mechanism configured to move the roughness measuring instrument and the measured object three-dimensionally relative to each other so that the roughness measuring instrument traces the measured surface; and a control unit configured to control operations of the roughness measuring instrument and the relative moving mechanism, the control unit including: a measuring force command module configured to output a measuring command which designates a direction and a magnitude of the measuring force; and a measuring force control module configured to control the direction and magnitude of the measuring force which is generated by the measuring force application unit by issuing a control signal to the measuring force application unit, wherein the measuring force control module monitors a displacement detection signal from the displacement detector and issues the control signal to the measuring force application unit so as to instruct the measuring force application unit to generate therein the measuring force whose magnitude and direction are designated by the measuring force command when a displacement speed of the measuring arm is equal to or slower than a predetermined threshold, and the measuring force control module applies a feedback to the measuring force application unit so as to instruct the measuring force application unit to generate therein a force in a direction in which the distal end of the measuring arm is raised upwards when the displacement speed of the measuring arm exceeds the predetermined threshold. a roughness measuring instrument configured to measure a surface property of a measured surface of a measured object by tracing the measured surface while being kept in contact with the measured surface, the roughness measuring instrument including: a measuring arm supported so as to make an arc-like movement about a rotating shaft as a fulcrum; a stylus (233U, 233D) provided at a distal end of the measuring arm; a displacement detector configured to detect a displacement of the measuring arm which occurs as a result of the measuring arm having made an arc-like movement; and a measuring force application unit configured to bias the measuring arm in a direction in which the measuring arm makes an arc-like movement to thereby apply a measuring force to the stylus (233U, 233D); a measuring arm supported so as to make an arc-like movement about a rotating shaft as a fulcrum; a stylus (233U, 233D) provided at a distal end of the measuring arm; a displacement detector configured to detect a displacement of the measuring arm which occurs as a result of the measuring arm having made an arc-like movement; and a measuring force application unit configured to bias the measuring arm in a direction in which the measuring arm makes an arc-like movement to thereby apply a measuring force to the stylus (233U, 233D); a relative moving mechanism configured to move the roughness measuring instrument and the measured object three-dimensionally relative to each other so that the roughness measuring instrument traces the measured surface; and a control unit configured to control operations of the roughness measuring instrument and the relative moving mechanism, the control unit including: a measuring force command module configured to output a measuring command which designates a direction and a magnitude of the measuring force; and a measuring force control module configured to control the direction and magnitude of the measuring force which is generated by the measuring force application unit by issuing a control signal to the measuring force application unit, wherein a measuring force command module configured to output a measuring command which designates a direction and a magnitude of the measuring force; and a measuring force control module configured to control the direction and magnitude of the measuring force which is generated by the measuring force application unit by issuing a control signal to the measuring force application unit, wherein the measuring force control module monitors a displacement detection signal from the displacement detector and issues the control signal to the measuring force application unit so as to instruct the measuring force application unit to generate therein the measuring force whose magnitude and direction are designated by the measuring force command when a displacement speed of the measuring arm is equal to or slower than a predetermined threshold, and the measuring force control module applies a feedback to the measuring force application unit so as to instruct the measuring force application unit to generate therein a force in a direction in which the distal end of the measuring arm is raised upwards when the displacement speed of the measuring arm exceeds the predetermined threshold.