An f-theta lens is composed of a negative lens element of a negative power, and second and third lens elements of a positive power, arranged in this order from the side of a optical deflection device, wherein at least one surface of the lens elements is a cylindrical surface that has a refractive power only in the deflecting direction. The f-theta lens satisfies the conditions: N1>N2=N3, υ1<υ2=υ3, and 4<=|f23 / f1.D0|<=16, wherein N1, N2 and N3 represent refractive indexes, υ1, υ2 and υ3 Abbe constants of the first to third lens elements respectively, f1 the focal length of the first lens element, f23 the composite focal length of the second and third lens elements, and D0 a distance from the optical deflection device to the lens surface of the first lens element.