Provided is an optical system with an excellent anti-reflection effect and ghost suppression effect including an aspherical lens having at least one of an incident surface and an exiting surface of an optical glass formed of an aspherical surface, in which: the aspherical surface includes an anti-reflection structure formed thereon, the anti-reflection structure having an anti-reflection function and including multiple inorganic structural parts finer than a used wavelength; and the aspherical surface has a point that satisfies the following expression: |(1/Rm−1/Rs)/Rm|>5.0×10−5, where Rm denotes a radius of curvature in a meridional direction at an arbitrary point, and Rs denotes a radius of curvature in a sagittal direction at the arbitrary point.