A Fresnel lens and a pyroelectricity sensor module are provided. The Fresnel lens includes unit lens groups having different refractive indexes, and each of the unit lens groups includes unit lenses. Between two unit lenses of the same unit lens group at least one unit lens included in a different lens group is arranged. The pyroelectricity sensor module includes a Fresnel lens which condenses infrared light; a detecting sensor disposed to receive the condensed infrared light and detect the infrared light; and a signal processing board on which the detecting sensor is mounted and configured to control an output signal of the detecting sensor. The Fresnel lens includes unit lens groups having different refractive indexes, and each of the unit lens groups includes unit lenses, and between two unit lenses of the same unit lens group, at least one unit lens included in a different lens group is arranged.