PURPOSE: To obtain a spectroscopic method for object image and its device capable of obtaining continuous spectroscopic image of a measured object in the case where a camera and a measured object are relatively moving such case as that the measured object moving against a fixed camera is imaged or that the camera is moved against a still measured object to take in image.

CONSTITUTION: A camera 4 having a continuous interference filter 6 in which transmitting light wave length continuousely changes in one direction in a determined wave length range and a two dimensional image sensor 7 arranged so that sensor elements receive the transmitting light with certain wave lengths minutely separating the determined wave length range for each line, is used and the camera 4 and a measured object 3 are relatively moved in one direction. During the relative movement, the image of the measured object 3 focused on the two dimensional image sensor 7 is taken with the camera 4 at every determined relative movement interval. The light intensity data at every specific wave length of each pixel in the image obtained for the measured object are stored in the memory 18 as image information and the image information is read out of the memory 18.