Provided is a surveying instrument that: provides some or all of the required parameters for position and posture for a surveying method in which surveying instruments that receive light beams are arranged in a row; reduces the causes of errors; and improves surveying precision. The surveying instrument has: at least one light-emission port capable of emitting light from a variable-wavelength light source; and at least one light-receiving section that receives light emitted from or reflected from an adjacent surveying instrument. Light emitted from the light-emission port is in a fan-shaped pattern and is emitted in a direction vertical to the direction in which the fan shape spreads, such that the emission angle changes as a monotonic function of the wavelength of the light. At least one parameter for the relative position and the posture of the surveying instrument is measured by finding either the wavelength of the light emitted and received by adjacent surveying instruments or the wavelength of light reflected by an adjacent surveying instrument and received by the surveying instrument that emitted said light.
