A method for automatic elevator installation, characterised by the steps of: marking each door opening (DO1-DO4 in the elevator shaft with downwards facing door reflectors (DR1a-DR4a, DR1b-DR4b) positioned at opposite sides of the door opening (DO1-DO4), positioning a robotic total station at a bottom of the elevator shaft and creating a reference coordinate system of the elevator shaft with the robotic total station, measuring the position of the door reflectors (DR1a-DR4a, DR1b-DR4b) in relation to the elevator shaft with the robotic total station, fitting straight door lines (DL1, DL2) to the measurements, said straight door lines (DL1, DL2) forming virtual plumb lines for the doors in the elevator shaft, marking the predetermined positions (A2, B2) of the guide rails (51, 52, 53, 54) on the bottom of the elevator shaft based on the dimensions of the elevator shaft and the elevator car, installing the lowermost guide rails (51, 52, 53, 54) manually to the elevator shaft based on the predetermined positions (A2, B2) of the guide rails (51, 52, 53, 54), forming vertical guide rail lines (GL1, GL2) with the robotic total station based on the door lines (DL1, DL2), said vertical guide rail lines (GL1, GL2) forming virtual plumb lines for the guide rails (51, 52, 53, 54) in the elevator shaft, providing an upwards and downwards along the car guide rails (51, 52) movable installation platform in the elevator shaft, positioning downwards facing platform reflectors (PR1-PR3) on a bottom of the installation platform, measuring the position of the platform reflectors (PR1-PR3) in relation to the elevator shaft with the robotic total station, whereby the orientation and the position of the installation platform in relation to the elevator shaft can be determined. marking each door opening (DO1-DO4 in the elevator shaft with downwards facing door reflectors (DR1a-DR4a, DR1b-DR4b) positioned at opposite sides of the door opening (DO1-DO4), positioning a robotic total station at a bottom of the elevator shaft and creating a reference coordinate system of the elevator shaft with the robotic total station, measuring the position of the door reflectors (DR1a-DR4a, DR1b-DR4b) in relation to the elevator shaft with the robotic total station, fitting straight door lines (DL1, DL2) to the measurements, said straight door lines (DL1, DL2) forming virtual plumb lines for the doors in the elevator shaft, marking the predetermined positions (A2, B2) of the guide rails (51, 52, 53, 54) on the bottom of the elevator shaft based on the dimensions of the elevator shaft and the elevator car, installing the lowermost guide rails (51, 52, 53, 54) manually to the elevator shaft based on the predetermined positions (A2, B2) of the guide rails (51, 52, 53, 54), forming vertical guide rail lines (GL1, GL2) with the robotic total station based on the door lines (DL1, DL2), said vertical guide rail lines (GL1, GL2) forming virtual plumb lines for the guide rails (51, 52, 53, 54) in the elevator shaft, providing an upwards and downwards along the car guide rails (51, 52) movable installation platform in the elevator shaft, positioning downwards facing platform reflectors (PR1-PR3) on a bottom of the installation platform, measuring the position of the platform reflectors (PR1-PR3) in relation to the elevator shaft with the robotic total station, whereby the orientation and the position of the installation platform in relation to the elevator shaft can be determined.