Diffraction element

A diffraction element comprising:

• an optically-anisotropic layer that has a liquid crystal alignment pattern in which an orientation of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction,
• wherein a birefringence Δn of the optically-anisotropic layer is 0.20 or more,
• the optically-anisotropic layer includes a surfactant, and
• in a case where components of the optically-anisotropic layer in a depth direction are analyzed by time-of-flight secondary ion mass spectrometry while irradiating the optically-anisotropic layer with an ion beam from one surface to another surface of the optically-anisotropic layer, a depth-direction profile of a secondary ion intensity derived from the surfactant is obtained, a depth position corresponding to a thickness of 20% from the one surface to the other surface side of the optically-anisotropic layer is represented by a position D20, a depth position corresponding to a thickness of 80% from the one surface to the other surface side of the optically-anisotropic layer is represented by a position D80, and an average value of secondary ion intensities derived from the surfactant between the position D20 and the position D80 is calculated, in a region from the position D20 to the position D80, a peak that shows a secondary ion intensity having a size of 1.1 times or more the average value is observed and a peak that shows a secondary ion intensity having a size of 5 times or more the average value is not observed.