MALFUNCTION DIAGNOSIS APPARATUS

This malfunction diagnosis apparatus includes detection means (2), setting means (3), calculation means (5), and diagnosis means (6). The detection means (2) detects a line on a road surface by distinguishing the line from an asphalt surface other than the line. The setting means (3) sets a first area corresponding to the line and a second area corresponding to the asphalt surface using a first image capturedwhile the line is detected. The calculation means (5) calculates a first brightness in the first area and a second brightness in the second area using a second image captured while a vehicle is cruising and the line is not detected. The diagnosis means (6) diagnoses the malfunction based on at least one of the first brightness and the second brightness.