A head-up display system, comprising: an image-forming and projection device that forms a display image, and projects projection light of the display image that is formed; a combiner that allows the projection light of the display image, which is projected from the image-forming and projection device in a case of being disposed at an in- use position, to be transmitted through the combiner, and forms a virtual image of the display image, which provides information to a user, at a transmission destination; a housing that includes an opening through which the projection light of the display image from the image- forming and projection device passes to reach the combiner in use, and accommodates the image-forming and projection device and the combiner in non-use in an inner side; a first drive device that drives the combiner between a non-use position at which the combiner is accommodated in an inner side of the housing, and the in-use position at which the combiner is erected on an outer side of the housing; a lid body that covers the opening in non-use of the combiner, and is accommodated on an inner side of the housing in use of the combiner and opens the opening; and a second drive device that drives the lid body between a position at which the lid body covers the opening, and a position at which the lid body opens the opening, wherein the lid body includes at least a first divided lid body and a second divided lid body which engage with each other at the time of covering the opening, characterized in that the first divided lid body includes an optical path regulator that regulates an optical path of the projection light of the display image projected from the image-forming and projection device in use of the combiner on an inner side of the housing, and allows projection light, which is necessary for formation of the virtual image of the display image through the combiner, to pass through the optical path regulator, and the second divided lid body includes a covering member that covers the optical path regulator at the time of covering the opening. an image-forming and projection device that forms a display image, and projects projection light of the display image that is formed; a combiner that allows the projection light of the display image, which is projected from the image-forming and projection device in a case of being disposed at an in- use position, to be transmitted through the combiner, and forms a virtual image of the display image, which provides information to a user, at a transmission destination; a housing that includes an opening through which the projection light of the display image from the image- forming and projection device passes to reach the combiner in use, and accommodates the image-forming and projection device and the combiner in non-use in an inner side; a first drive device that drives the combiner between a non-use position at which the combiner is accommodated in an inner side of the housing, and the in-use position at which the combiner is erected on an outer side of the housing; a lid body that covers the opening in non-use of the combiner, and is accommodated on an inner side of the housing in use of the combiner and opens the opening; and a second drive device that drives the lid body between a position at which the lid body covers the opening, and a position at which the lid body opens the opening, wherein the lid body includes at least a first divided lid body and a second divided lid body which engage with each other at the time of covering the opening, characterized in that the first divided lid body includes an optical path regulator that regulates an optical path of the projection light of the display image projected from the image-forming and projection device in use of the combiner on an inner side of the housing, and allows projection light, which is necessary for formation of the virtual image of the display image through the combiner, to pass through the optical path regulator, and the second divided lid body includes a covering member that covers the optical path regulator at the time of covering the opening.