A measurement method using a tracking type laser interferometer that includes: a recursive reflector for reflecting incident measurement light and returning the same in the incident direction; a main body having means for emitting measurement light, means for receiving return light reflected by the recursive reflector and returned therefrom, and means for controlling the emission direction of measurement light so that the distance between both optical axes of measurement light and return light becomes constant at all times, and outputs a measurement value in response to an increase or a decrease in distance between a reference point in the main body and the recursive reflector; and controlling means for controlling the means for controlling the emission direction, the method comprising the steps of: disposing at least one light reflecting means in an optical path between the main body and recursive reflector; and changing the directions of the optical axes of measurement light and return light; characterized in that the at least one light reflecting means is disposed taking into account a virtual image position of the reference point, which is formed by disposition of the light reflecting means, and measurement is carried out utilizing the virtual image position of the reference point, which is formed by disposition of the light reflecting means, as the reference point, by controlling the means for controlling the emission direction by the controlling means so that the measurement light reflected by the at least one light reflecting means is turned to the recursive reflector. a recursive reflector for reflecting incident measurement light and returning the same in the incident direction; a main body having means for emitting measurement light, means for receiving return light reflected by the recursive reflector and returned therefrom, and means for controlling the emission direction of measurement light so that the distance between both optical axes of measurement light and return light becomes constant at all times, and outputs a measurement value in response to an increase or a decrease in distance between a reference point in the main body and the recursive reflector; and controlling means for controlling the means for controlling the emission direction, the method comprising the steps of: disposing at least one light reflecting means in an optical path between the main body and recursive reflector; and changing the directions of the optical axes of measurement light and return light; characterized in that the at least one light reflecting means is disposed taking into account a virtual image position of the reference point, which is formed by disposition of the light reflecting means, and measurement is carried out utilizing the virtual image position of the reference point, which is formed by disposition of the light reflecting means, as the reference point, by controlling the means for controlling the emission direction by the controlling means so that the measurement light reflected by the at least one light reflecting means is turned to the recursive reflector. disposing at least one light reflecting means in an optical path between the main body and recursive reflector; and changing the directions of the optical axes of measurement light and return light; characterized in that the at least one light reflecting means is disposed taking into account a virtual image position of the reference point, which is formed by disposition of the light reflecting means, and measurement is carried out utilizing the virtual image position of the reference point, which is formed by disposition of the light reflecting means, as the reference point, by controlling the means for controlling the emission direction by the controlling means so that the measurement light reflected by the at least one light reflecting means is turned to the recursive reflector.