The TFT substrate (105) is provided with: a gate metal layer (3) which comprises a gate electrode (3G) and a patch electrode (3PE) of a TFT (10); a gate insulating layer (4) which is formed on the gate metal layer and has a first opening (4a) that reaches the patch electrode; a source metal layer (7) which is formed on the gate insulating layer and comprises a source electrode (7S), a drain electrode (7D) and a drain extension part (7de) extended from the drain electrode of the TFT; an interlayer insulating layer (11) which is formed on the source metal layer and has a second opening (11a) that overlaps the first opening when viewed from the normal direction of a dielectric substrate (1) and a third opening (11b) that reaches the drain extension part; and a conductive layer (19) which is formed on the interlayer insulating layer and comprises a patch-drain connection part (19a). The patch-drain connection part is in contact with the patch electrode within the first opening, while beingin contact with the drain extension part within the third opening.