Provided is a product that is able to produce good foam even from a screen foamer composition using a nonionic surfactant. This foam contains a nonionic surf actant, comprises an air layer and a foam shell encapsulating said air layer, and is characterized in that: the foam shell has a high light transmission region which is optically transparent and a low light transmission region which is less optically transparent than the high light transmission region, both regions being disposed so as to extend across the surface of the foam shell in such a manner as to form an identifiable boundary therebetween； and when the foam is left still at 25°C or lower, the area occupied by the low light transmission region grows over time with respect to the surface area of the foam shell so as to cause the entire surface of the foam shell to end up being occupied by the low light transmission region.
