An in-vehicle device including: a drive assist unit configured to perform drive assist processing that assists an occupant in driving a vehicle; and a display unit being a head-up display configured to display an image in a display area with the image overlapped on a scene in a real space ahead of the vehicle, the in-vehicle device comprising a display control unit configured to control the display unit to display, in a normal state while the drive assist processing is performed by the drive assist unit, an image of a first marker at a vehicle-corresponding position as a position in the display area corresponding to a position where the vehicle is estimated to be positioned in the real space in a predetermined time, wherein the first marker has a first color, the first marker has a first shape that fluctuates, and a display position of the first marker varies periodically from the vehicle-corresponding position, wherein the display control unit is configured to control the display unit to display an image of a second marker when there is a need to issue an alert to the occupant; the second marker has a second shape that differs from the first shape, characterized in that the second marker has a second color that differs from the first color; and a display position of the second marker moves from the vehicle-corresponding position to a position in the display area corresponding to a position on the front windshield glass, which corresponds to a location in the real space where an attention of the occupant is required, at a speed higher than a speed at which the display position of the first marker varies, wherein the display control unit is configured to control the display unit to display an image of a third marker when a failure is occurred in the drive assist unit or in the drive assist processing performed by the drive assist unit; the third marker has a third color that differs from the first color and the second color; and the third marker has a third shape that differs from the first shape and the second shape. a drive assist unit configured to perform drive assist processing that assists an occupant in driving a vehicle; and a display unit being a head-up display configured to display an image in a display area with the image overlapped on a scene in a real space ahead of the vehicle, the in-vehicle device comprising a display control unit configured to control the display unit to display, in a normal state while the drive assist processing is performed by the drive assist unit, an image of a first marker at a vehicle-corresponding position as a position in the display area corresponding to a position where the vehicle is estimated to be positioned in the real space in a predetermined time, wherein the first marker has a first color, the first marker has a first shape that fluctuates, and a display position of the first marker varies periodically from the vehicle-corresponding position, wherein the display control unit is configured to control the display unit to display an image of a second marker when there is a need to issue an alert to the occupant; the second marker has a second shape that differs from the first shape, characterized in that the second marker has a second color that differs from the first color; and a display position of the second marker moves from the vehicle-corresponding position to a position in the display area corresponding to a position on the front windshield glass, which corresponds to a location in the real space where an attention of the occupant is required, at a speed higher than a speed at which the display position of the first marker varies, wherein the display control unit is configured to control the display unit to display an image of a third marker when a failure is occurred in the drive assist unit or in the drive assist processing performed by the drive assist unit; the third marker has a third color that differs from the first color and the second color; and the third marker has a third shape that differs from the first shape and the second shape.