A synthetic resin multilayer bottle comprising: an outer shell bottle which has a cylindrical outer opening part, a shoulder part connected to the outer opening part, a trunk part connected to the shoulder part, a bottom part connected to the trunk part, and a ground contact part connected to the bottom part, and which is capable of restoring an original shape thereof from deformation caused by pressing; an inner container body which has a cylindrical inner opening part provided on an inner circumferential side of the outer opening part of the outer shell bottle, and an inner container main body connected to the inner opening part and shaped along an inner surface shape of the outer shell bottle, and which deforms in response to pressing; and an air channel which is formed between the outer opening part and the inner opening part and through which outside air is introduced between the outer shell bottle and the inner container body, a content composed of a liquid seasoning that contains soy sauce being held in the inner container body, wherein the outer shell bottle and the inner container body are composed of a polyester resin, characterized in that the inner container body contains an oxygen barrier agent in a range of 3 to 10 percent by mass of a resin constituting the inner container body, and in that the synthetic resin multilayer bottle has oxygen permeability such that, after the inner container body is fully filled with distilled water from which dissolved oxygen has been removed, the inner opening part is sealed, and the distilled water is allowed to stand for 60 days at a temperature of 20°C while keeping the air channel between the outer shell bottle and the inner container body open, the amount of dissolved oxygen in the distilled water is 3 ppm or less. an outer shell bottle which has a cylindrical outer opening part, a shoulder part connected to the outer opening part, a trunk part connected to the shoulder part, a bottom part connected to the trunk part, and a ground contact part connected to the bottom part, and which is capable of restoring an original shape thereof from deformation caused by pressing; an inner container body which has a cylindrical inner opening part provided on an inner circumferential side of the outer opening part of the outer shell bottle, and an inner container main body connected to the inner opening part and shaped along an inner surface shape of the outer shell bottle, and which deforms in response to pressing; and an air channel which is formed between the outer opening part and the inner opening part and through which outside air is introduced between the outer shell bottle and the inner container body, a content composed of a liquid seasoning that contains soy sauce being held in the inner container body, wherein the outer shell bottle and the inner container body are composed of a polyester resin, characterized in that the inner container body contains an oxygen barrier agent in a range of 3 to 10 percent by mass of a resin constituting the inner container body, and in that the synthetic resin multilayer bottle has oxygen permeability such that, after the inner container body is fully filled with distilled water from which dissolved oxygen has been removed, the inner opening part is sealed, and the distilled water is allowed to stand for 60 days at a temperature of 20°C while keeping the air channel between the outer shell bottle and the inner container body open, the amount of dissolved oxygen in the distilled water is 3 ppm or less.