A semiconductor device for outputting a message image (C11, C21) to be projected onto a projection area on a road surface, the projection area having a position (P1, P2) located at a predetermined distance ahead of a vehicle, the semiconductor device comprising: a position estimation circuit configured to estimate a position of the vehicle at a scheduled time when the message image (C11, C21) is to be projected, on the basis of movement information of the vehicle and a position of the vehicle at a time when the movement information is received; a reference image signal output circuit configured to determine the position (P1, P2) of the projection area onto which the message image (C11, C21) is to be projected at the scheduled time, on the basis of the estimated position of the vehicle at the scheduled time and the predetermined distance, and to output a reference image (C10, C15, C20) to be projected onto the determined position (P1, P2) of the projection area at the scheduled time; a test image signal acquisition circuit configured to acquire a test image obtained by imaging the projection area onto which the reference image (C10, C15, C20) is projected; a comparison circuit configured to compare the reference image (C10, C15, C20) with the test image; an image adjustment circuit configured to adjust pixel values of the message image (C11, C21) based on the comparison of the reference image (C10, C15, C20) and the test image; and an output circuit configured to output the adjusted message image (C11, C21) to be projected on the projection area; wherein the reference image signal output circuit is further configured to output the reference image (C10, C15, C20) at a time based on the estimated position of the vehicle at the schedule time and a running speed of the vehicle. a position estimation circuit configured to estimate a position of the vehicle at a scheduled time when the message image (C11, C21) is to be projected, on the basis of movement information of the vehicle and a position of the vehicle at a time when the movement information is received; a reference image signal output circuit configured to determine the position (P1, P2) of the projection area onto which the message image (C11, C21) is to be projected at the scheduled time, on the basis of the estimated position of the vehicle at the scheduled time and the predetermined distance, and to output a reference image (C10, C15, C20) to be projected onto the determined position (P1, P2) of the projection area at the scheduled time; a test image signal acquisition circuit configured to acquire a test image obtained by imaging the projection area onto which the reference image (C10, C15, C20) is projected; a comparison circuit configured to compare the reference image (C10, C15, C20) with the test image; an image adjustment circuit configured to adjust pixel values of the message image (C11, C21) based on the comparison of the reference image (C10, C15, C20) and the test image; and an output circuit configured to output the adjusted message image (C11, C21) to be projected on the projection area; wherein the reference image signal output circuit is further configured to output the reference image (C10, C15, C20) at a time based on the estimated position of the vehicle at the schedule time and a running speed of the vehicle.