In a head-up display device, in accordance with lifting and lowering operations of a combiner, each protrusion of a combiner support moves along a guide portion, causing a cover-operation member to turn about a rotary axis in a direction in which a cover is opened or closed. The guide portion includes, from top in order: a first guide portion which engages with the protrusion in a first state (use state); a second guide portion which engages with the protrusion when the cover-operation member turns; and a third guide portion which engages with the protrusion in a second state (non-use state). The angle formed by the direction in which the first guide portion extends and the direction in which the third guide portion extends is less than the angle formed by the direction in which the first guide portion extends and the direction in which the second guide portion extends.