1. A coil sensitivity map generating method comprising: when a pixel value of a pixel p in a complex image C n obtained by conducting a calibration scan of an entire FOV for each of phased array coils Coil_n (n&equals;1−N, N&gE;2) is represented as C n (p), and a pixel value of a pixel p in an additive image A b &equals;&Sgr;&verbar;C n &verbar; obtained by adding absolute value images &verbar;C n &verbar; produced from said complex images C n is represented as A b (p), calculating a sensitivity factor S n (p) at a pixel p in a phased array coil Coil_n by: S n ( p )&equals; C n ( p )/ A b ( p ); n of the phased array coils Coil_n based on said sensitivity factors S n (p).