A surveying system comprising: a target unit including a reflection target and an encoder pattern showing an angle in a circumferential direction around a central axis of the target unit; a scanner device including a distance measuring unit configured to perform a distance measurement by transmitting distance measuring light and receiving reflected light, a scanning unit configured to rotationally irradiate the distance measuring light onto a measurement range, and an angle detector (35,37) configured to detect an irradiation direction of the distance measuring light, so as to acquire point cloud data and acquire measured coordinates of the reflection target by performing target scanning, the scanner device including an encoder pattern reading unit configured to optically read the encoder pattern, and an arithmetic control unit configured to determine an encoder pattern read angle based on a result of encoder pattern reading; and a leveling base configured to selectively allow either of the target unit and the scanner device to be removably mounted so as to share a central axis in a vertical direction, and having offset angles, being known, around the central axis with respect to each of the target unit and the scanner device when the target unit or the scanner device is mounted, characterized in that the arithmetic control unit is configured to calculate a direction angle of the leveling base based on the encoder pattern read angle of the target unit installed by mounting on the leveling base and the offset angle of the target unit, and calculate coordinates of an installation point of the target unit based on the measured coordinates of the reflection target of the target unit installed by mounting on the leveling base and the direction angle, and the arithmetic control unit is configured to calculate a direction angle of the scanner device based on the offset angle of the scanner device and the direction angle of the leveling base on which the scanner device is mounted. a target unit including a reflection target and an encoder pattern showing an angle in a circumferential direction around a central axis of the target unit; a scanner device including a distance measuring unit configured to perform a distance measurement by transmitting distance measuring light and receiving reflected light, a scanning unit configured to rotationally irradiate the distance measuring light onto a measurement range, and an angle detector (35,37) configured to detect an irradiation direction of the distance measuring light, a distance measuring unit configured to perform a distance measurement by transmitting distance measuring light and receiving reflected light, a scanning unit configured to rotationally irradiate the distance measuring light onto a measurement range, and an angle detector (35,37) configured to detect an irradiation direction of the distance measuring light, so as to acquire point cloud data and acquire measured coordinates of the reflection target by performing target scanning, the scanner device including an encoder pattern reading unit configured to optically read the encoder pattern, and an arithmetic control unit configured to determine an encoder pattern read angle based on a result of encoder pattern reading; and an encoder pattern reading unit configured to optically read the encoder pattern, and an arithmetic control unit configured to determine an encoder pattern read angle based on a result of encoder pattern reading; and a leveling base configured to selectively allow either of the target unit and the scanner device to be removably mounted so as to share a central axis in a vertical direction, and having offset angles, being known, around the central axis with respect to each of the target unit and the scanner device when the target unit or the scanner device is mounted, characterized in that the arithmetic control unit is configured to calculate a direction angle of the leveling base based on the encoder pattern read angle of the target unit installed by mounting on the leveling base and the offset angle of the target unit, and calculate coordinates of an installation point of the target unit based on the measured coordinates of the reflection target of the target unit installed by mounting on the leveling base and the direction angle, and the arithmetic control unit is configured to calculate a direction angle of the scanner device based on the offset angle of the scanner device and the direction angle of the leveling base on which the scanner device is mounted.