The object of the present invention is to provide a mouse model for allergic diseases such as atopic dermatitis, and a dermatitis mouse model with impaired skin-barrier function. The present inventors found out that a mouse that has been caused to completely lose the function of expressing profilaggrin protein and filaggrin protein by entirely or partially disrupting the endogenous gene encoding filaggrin by a genetic mutation such as deletion or replacement, can be used as a mouse model for allergic diseases or atopic dermatitis wherein the skin-barrier function has been impaired.