A projection system comprising: a video image converter configured to generate attitude data of a projector on a basis of motion data in projecting moving picture data, store the attitude data in a storage unit, correct the moving picture data in accordance with the attitude data, and store the corrected moving picture data in the storage unit; the projector configured to play back the corrected moving picture data stored in the storage unit and project the corrected moving picture data onto a projection plane; and a cradle configured to support the projector and change an attitude of the projector in accordance with the attitude data stored in the storage unit; wherein the video image converter includes a conversion synchronization unit configured to synchronize the moving picture data with the motion data, a conversion unit configured to convert the motion data into the attitude data, and a correction unit configured to correct the moving picture data in accordance with the motion data to generate the corrected moving picture data; and wherein the projector includes a moving picture playback unit configured to play back the corrected moving picture data stored in the storage unit, a projection synchronization unit configured to synchronize the played video image with the attitude data stored in the storage unit, a projection unit configured to project the synchronized video image onto the projection plane, and an attitude data supply unit configured to supply the synchronized attitude data to the cradle. a video image converter configured to generate attitude data of a projector on a basis of motion data in projecting moving picture data, store the attitude data in a storage unit, correct the moving picture data in accordance with the attitude data, and store the corrected moving picture data in the storage unit; the projector configured to play back the corrected moving picture data stored in the storage unit and project the corrected moving picture data onto a projection plane; and a cradle configured to support the projector and change an attitude of the projector in accordance with the attitude data stored in the storage unit; wherein the video image converter includes a conversion synchronization unit configured to synchronize the moving picture data with the motion data, a conversion unit configured to convert the motion data into the attitude data, and a correction unit configured to correct the moving picture data in accordance with the motion data to generate the corrected moving picture data; and a conversion synchronization unit configured to synchronize the moving picture data with the motion data, a conversion unit configured to convert the motion data into the attitude data, and a correction unit configured to correct the moving picture data in accordance with the motion data to generate the corrected moving picture data; and wherein the projector includes a moving picture playback unit configured to play back the corrected moving picture data stored in the storage unit, a projection synchronization unit configured to synchronize the played video image with the attitude data stored in the storage unit, a projection unit configured to project the synchronized video image onto the projection plane, and an attitude data supply unit configured to supply the synchronized attitude data to the cradle. a moving picture playback unit configured to play back the corrected moving picture data stored in the storage unit, a projection synchronization unit configured to synchronize the played video image with the attitude data stored in the storage unit, a projection unit configured to project the synchronized video image onto the projection plane, and an attitude data supply unit configured to supply the synchronized attitude data to the cradle.