A surveying instrument comprising a monopod which is movable and, in use, to be sequentially installed at least at a first installing point and a second installing point which is a predetermined position with respect to said first installing point and a surveying instrument main body which is provided at a known distance from a lower end of said monopod and at a known angle with respect to an axis of said monopod and has a reference optical axis, wherein said surveying instrument main body comprises a distance measuring unit configured to irradiate a distance measuring light, receive a reflected distance measuring light and measure a distance to an object to be measured, a measuring direction image pickup module in a predetermined relationship with said reference optical axis and configured to acquire imagery which includes said object to be measured, an attitude detector configured to detect a tilt of said surveying instrument main body with respect to the horizontal or the vertical and an arithmetic control module configured to make said distance measuring unit perform distance measurements of predetermined measuring points (2a, 2b, 2c) from said first installing point and said second installing point, respectively, and make said measuring direction image pickup module acquire images of said object to be measured, and wherein said arithmetic control module is configured to extract each common corresponding point from a first image acquired at said first installing point and a second image acquired at said second installing point, perform the matching of said first image and said second image based on the extracted common corresponding points, and make a measurement of a positional relationship of said object to be measured with respect to said first installing point and said second installing point by means of photogrammetry with a wide intersection angle based on the matched first and second images, wherein for a wide intersection angle H/B<2, with B denoting a length of a base line between two image pickup positions, with H denoting a shortest distance from said base line to a measuring point, and wherein the intersection angle (α, β1, β2) is defined by two lines that connect the respective image pickup positions and the measuring point, characterized in that said arithmetic control module, for performing said extracting each common corresponding point, is configured to: - acquire an auxiliary first image in a state where a worker tilts said monopod rightward or leftward with respect to said object to be measured after acquiring said first image at said first installing point; - perform photogrammetry with a narrow intersection angle (β1) based on said first image and said auxiliary first image, to calculate rough three-dimensional coordinates of said measuring points and of feature points extracted from said first image; - acquire an auxiliary second image in a state where a worker tilts said monopod rightward or leftward with respect to said object to be measured after acquiring said second image at said second installing point; - perform photogrammetry with a narrow intersection angle (β2) based on said second image and said auxiliary second image, to calculate rough three-dimensional coordinates of said measuring points and of feature points extracted from said second image; - compare the rough three-dimensional coordinates of the feature points in the first image and the rough three-dimensional coordinates of the feature points in the second image with reference to the measuring points, and to determine, as common corresponding points of the first image and the second image, any roughly-matched feature points. - acquire an auxiliary first image in a state where a worker tilts said monopod rightward or leftward with respect to said object to be measured after acquiring said first image at said first installing point; - perform photogrammetry with a narrow intersection angle (β1) based on said first image and said auxiliary first image, to calculate rough three-dimensional coordinates of said measuring points and of feature points extracted from said first image; - acquire an auxiliary second image in a state where a worker tilts said monopod rightward or leftward with respect to said object to be measured after acquiring said second image at said second installing point; - perform photogrammetry with a narrow intersection angle (β2) based on said second image and said auxiliary second image, to calculate rough three-dimensional coordinates of said measuring points and of feature points extracted from said second image; - compare the rough three-dimensional coordinates of the feature points in the first image and the rough three-dimensional coordinates of the feature points in the second image with reference to the measuring points, and to determine, as common corresponding points of the first image and the second image, any roughly-matched feature points.