The object of the present invention is to provide a moldable sheet which maintains good moldability even in a case where the moldable sheet is kept at a low temperature and a low humidity. The moldable sheet comprises a porous material which a synthetic resin is coated on or impregnated into, the porous material being further impregnated with a water retention agent. The water retention agent in the porous material retains moisture in the porous material, maintaining the good moldability of the moldable sheet, even at a low temperature and a low humidity.