A chart 50 is formed of a density detecting pattern 51 and position detecting marks 52. The density detecting pattern 51 includes five different density areas A, B, C, D and E in form of belts arranged sequentially in Y-direction. The position detecting marks 52 are formed at intervals in X-direction which is a direction of arrangement of nozzles, at an end of the density area A of the density detecting pattern 51. These position detecting marks 52 are formed by suspending, for a fixed period of time, discharge from particular nozzles selected from a plurality of nozzles which discharge ink for forming the density detecting pattern 51, thereby producing ink-free portions (void portions) in the density area A.