A semiconductor device which is mounted in a mobile having therein a projecting device and a camera for imaging a periphery of the mobile, and outputs a message image signal being a signal of a message image to be projected onto the periphery of the mobile, the semiconductor device comprising: a first area decision part which decides based on movement information of the mobile, a first area being an area onto which the message image is projected at a first time being a schedule time when the message image is to be projected; a delay period calculation part which calculates a delay period being a period from the first time when the message image is projected onto the first area to a second time when the message image is projectable; a second area decision part which adjusts the first area on the basis of the movement information and the delay period to decide a second area; an image signal conversion part which converts the message image signal according to the second area; a message image output part which outputs the message image signal converted by the image signal conversion part; an internal memory which stores a reference image signal that is a signal of a reference image; a reference image signal output part which outputs the stored reference image signal to the projecting device to project the reference image onto a projection area being the area onto which the message image is projected; a test image signal acquisition part which acquires a test image signal being a signal of a test signal obtained by imaging the projection area onto which the reference image is projected; a comparison part which compares the stored reference image signal with the test image signal; an image adjustment part which adjusts the message image signal on the basis of the result of comparison therebetween; an adjustment signal acquisition part which acquires an adjustment signal from another mobile which is positioned around the mobile and in which another semiconductor device having the same configuration as the semiconductor device, a projecting device and a camera for imaging a periphery of the another mobile are mounted; and an adjustment signal output part, wherein the image adjustment part adjusts a message image in terms of brightness value on the basis of the adjustment signal acquired from the another mobile, wherein the message image output part outputs the message image signal converted by the image signal conversion part and adjusted by the image adjustment part, and wherein the adjustment signal output from the another semiconductor device is a signal generated by the another semiconductor device as a result of comparing a test image signal obtained by imaging the projection area onto which the reference image is projected by the mobile, with the reference image signal stored in the another semiconductor device. a first area decision part which decides based on movement information of the mobile, a first area being an area onto which the message image is projected at a first time being a schedule time when the message image is to be projected; a delay period calculation part which calculates a delay period being a period from the first time when the message image is projected onto the first area to a second time when the message image is projectable; a second area decision part which adjusts the first area on the basis of the movement information and the delay period to decide a second area; an image signal conversion part which converts the message image signal according to the second area; a message image output part which outputs the message image signal converted by the image signal conversion part; an internal memory which stores a reference image signal that is a signal of a reference image; a reference image signal output part which outputs the stored reference image signal to the projecting device to project the reference image onto a projection area being the area onto which the message image is projected; a test image signal acquisition part which acquires a test image signal being a signal of a test signal obtained by imaging the projection area onto which the reference image is projected; a comparison part which compares the stored reference image signal with the test image signal; an image adjustment part which adjusts the message image signal on the basis of the result of comparison therebetween; an adjustment signal acquisition part which acquires an adjustment signal from another mobile which is positioned around the mobile and in which another semiconductor device having the same configuration as the semiconductor device, a projecting device and a camera for imaging a periphery of the another mobile are mounted; and an adjustment signal output part, wherein the image adjustment part adjusts a message image in terms of brightness value on the basis of the adjustment signal acquired from the another mobile, wherein the message image output part outputs the message image signal converted by the image signal conversion part and adjusted by the image adjustment part, and wherein the adjustment signal output from the another semiconductor device is a signal generated by the another semiconductor device as a result of comparing a test image signal obtained by imaging the projection area onto which the reference image is projected by the mobile, with the reference image signal stored in the another semiconductor device.