An imaging device includes an image sensor and a lens assembly. The lens assembly includes at least six lenses sequentially aligned along an optical axis from a first lens, to focus or guide light to the image sensor. The at least six lenses include: a first lens farthest from the image sensor and having positive refractive power, a second lens, disposed between the first lens and the image sensor and has negative refractive power, a third lens, disposed between the second lens and the image sensor and has positive refractive power, a fourth lens, disposed between the third lens and the image sensor and has negative refractive power, a fifth lens, disposed between the fourth lens and the image sensor and has positive refractive power, and a sixth lens, disposed between the fifth lens and the image sensor and has negative refractive power.