A polarizer having at least one optical film and at least one polarizing film, wherein the absolute value of the photo-elastic coefficient C of the optical film is 2×10−12 Pa−1 or more, the optical film has an in-plane direction in which the sound propagation velocity is the maximum, and the angle between the in-plane direction in which the sound propagation velocity through the optical film is the maximum and the direction of the absorption axis of the polarizing film falls within a range of from 0° to less than 45°, is excellent in working aptitude and can prevent optical unevenness of the liquid-crystal display device accompanied by environmental changes.