The present technology relates to a solid state imaging sensor that is possible to suppress the reflection of incident light with a wide wavelength band. A reflectance adjusting layer is provided on the substrate in an incident direction of the incident light with respect to the substrate such as Si and configured to adjust reflection of the incident light on the substrate. The reflectance adjusting layer includes a first layer formed on the substrate and a second layer formed on the first layer. The first layer includes a concavo-convex structure provided on the substrate and a material which is filled into a concave portion of the concavo-convex structure and has a refractive index lower than that of the substrate, and the second layer includes a material having a refractive index lower than that of the first layer. It is possible to reduce the reflection on the substrate such as Si by using the principle of the interference of the thin film. Such a technology can be applied to solid state imaging sensors.