1. An electron microscope provided with an irradiation unit for irradiating an object under observation with an electron beam, first and second image detection units for detecting a response from the object under observation, respectively, a transfer unit for holding and transferring the object under observation, a tilting unit capable of optionally setting a tilt-angle of the object under observation, a rotation unit capable of optionally setting a rotation-angle of the object under observation, and an operation unit for executing various operations, the electron microscope comprising: a first storage means for tilting the object under observation at angle steps differing from each other, and storing a first tilted-image group acquired by a photographing unit; a rotation means for correcting misregistration of the object under observation by a rotation step-angle to thereby rotate the object under observation up to a set rotation angle; a second storage means for tilting the object under observation rotated by the rotation means, at angle-steps differing from each other, and storing a second tilted-image group acquired by a photographing unit; and an operation means for creating third, and fourth reconstruction images, obtained by correcting misregistrations of first and second reconstruction images, respectively, the first and second reconstruction images, being created from the first and second tilted-image groups, respectively, and creating a fifth reconstruction image by superimposing the third, and fourth reconstruction images one on the other.