To provide a polymeric material having excellent dimensional stability at high temperatures, processability and ionic conductivity and especially useful as an ionic conductive film with an aromatic polyethereal compound comprising a sulfonic acid group introduced thereinto and useful as polyelectrolytic membranes.

The sulfonated aromatic polyethereal compound is characterized as comprising a constituent unit represented by general formula (1) and general formula (2). A material having not only the ionic conductivity but also heat resistance and processability and exhibiting performances outstanding as a polyelectrolyte such as a fuel cell can be provided by the sulfonated aromatic polyethereal compound. The sulfonated aromatic polyethereal compound can be applied to various kinds of electrolytes of cells or batteries, display elements, sensors, signal transmission media, capacitors, electrodialytic, electrolytic membranes, etc.