A semiconductor device includes: a first substrate; a gate electrode on the first substrate; a gate insulating layer on the gate electrode; an oxide semiconductor film including a channel region disposed over the gate electrode through the gate insulating layer and lowered-resistance region contacting the channel region; a source electrode and a drain electrode on the channel region; a first insulating film covering at least the channel region and including a contact hole that exposes the lowered-resistance region; and a second insulating film having reducing characteristics and disposed above the first insulating film across the contact hole, the second insulating film contacting the lowered-resistance region inside the contact hole.