Supports for a railroad vehicle are accurately detected by using a support detection device using laser measurement and provided with: two or more scanning laser range finders (15, 16) that are provided at positions apart from each other in a tie direction from the center on the roof of a railroad vehicle (14), and each scan an outdoor support (12), a tunnel support (13), and a tunnel ceiling (17) above the vehicle (14) by the scan angle rotating about a rotation axis in the tie direction ; and a support detection unit (21) that, on the basis of data relating to a distance (d) and an angle (theta) to a scan spot irradiated with laser from the scanning laser range finders (15, 16), detects the outdoor support (12) or the tunnel support (13).