Method of manufacturing an active matrix substrate, a display panel, and a display device

A drain electrode (17) includes (i) a lower drain electrode (17a) stacked on a semiconductor layer (14) so as to partially cover an upper surface of the semiconductor layer (14) and (ii) an upper drain electrode (17b). The semiconductor layer (14), the lower drain electrode (17a), and the upper drain electrode (17b) form steps. In a step part where the steps are formed, a distance between a periphery of the lower drain electrode (17a) and a periphery of the upper drain electrode (17b) is more than 0.4 µm but less than 1.5 µm.