A feed additive for laying hens comprising lactobionic acid or a lactobionic acid salt and a feed characterized by containing a feed additive for laying hens comprising lactobionic acid or a lactobionic acid salt and a feed. Namely, a feed additive for laying hens, which is excellent in effect of reinforcing eggshells, shows a particularly remarkable effect of improving eggshell qualities in the second half of the laying period, relieves stress caused by forced molting, cage transfer and so on and can inhibit lowering in the egg-laying rate.
