Synthetic resin tube structure

A synthetic resin tube structure including a first synthetic-resin member which includes a flange having a plurality of bores formed therein, and a plurality of first divided pipes formed integrally with the flange; and a second synthetic-resin member which includes a plurality of second divided pipes, and a connector to connect the plurality of second divided pipes to each other. In the synthetic resin tube structure, the plurality of first and second divided pipes are subjected to vibration welding to form a plurality of pipes respectively having therein passages which communicate with the respective corresponding bores, and the vibration welding is performed while a direction, in which the plurality of first and second divided pipes are vibrated, is inclined at an angle with respect to a reference plane in a direction perpendicular to an axial direction of each of the bores formed in the flange.