To appropriately spout a content liquid in a bottle body constituted so that a fading deformation of an inner layer near a bottom part accompanied with spouting of the content liquid can smoothly and sufficiently advance without an external force in a blow molded bottle body made of a synthetic resin being a delamination bottle assembled with a spouting cap with a valve.

The blow molded bottle body is formed by assembling a bottle body constituted of an outer layer in which an opening cylinder portion is raised from the upper end of a cylindrical barrel portion through a shoulder portion, and an external shell is formed, and an inner layer which is laminated on the outer layer so as to be releasable, and forms an inner bag body so as to perform fading deformation, with a spouting cap. In the bottle body, the shape from the barrel portion to the bottom part is made to be a flat cylindrical shape in which a flat cross-sectional shape is flattened in the before and behind direction, and the shape of the bottom part is made to be a shape expanding into a spherical arc shell shape flattened downward in the before and behind direction, and the spouting cap has a valve function which does not permit invasion of the external air.