ROAD SURFACE AREA DETECTION DEVICE

To provide a road surface area detection device that can detect a road surface area with a simple configuration. The road surface area detection device (10) includes a normalized speed calculation portion (25) configured to calculate a normalized speed (nv) based on a movement of a feature point (P) in an image captured by a camera (13) that is disposed in a vehicle (1); a determination range calculation portion (28) configured to calculate a road surface determination range (E), which is indicated by a magnitude of the normalized speed (nv), based on the normalized speeds (nv) of at least two feature points at different positions in a width direction (Dw) of the vehicle (1) in a predetermined central area (cp) where the vehicle (1) is positioned in a center thereof in the width direction (Dw) perpendicular to a vehicle traveling direction (Dm); and a road surface area identification portion (29) configured to identify, as a road surface area (Ar) on which the vehicle (1) travels, a position in the width direction (Dw) that includes the feature point (P) whose normalized speed (nv) is within the road surface determination range (E).