PURPOSE: To obtain a convergence check device with high accuracy by image projecting in time series dots of R, G, B at a point in the center and N points in the circumference of an effective screen of a color cathode ray tube to be checked and photographing them by (N+1) set of cameras.

CONSTITUTION: R, G, B dots are image projected in time series on 9 points on the effective screen A of the color cathode ray tube CRT1 to be checked, the surrounding of the dots are close-up photographed by 9 sets of monochroic cameras CM1∼CM9 to provide to binary-coding circuits NT1∼NT9. Picture processing sections X1∼X9 connected to the binary-coding circuits NT1∼NT9 read in time series the dots of R, G, B from each binary-coding circuits NT1∼NT9 read in time series the dots of R, G, B from each binary-coding circuit by a data fetching command from a signal processing section Y, and the position data is transferred to the signal processing section Y. The position data of each dot transferred in time series to the signal processing section Y is signal-processed (operated) at the section Y and is image projected on a monitor color cathode ray tube CRT2.