The present invention provides a pentosan polysulfate which has a uronic acid content of from 0.0% by mass to 6.0% by mass, preferably a pentosan polysulfate which has a structure represented by general formula I, a pharmaceutically acceptable salt of one of these pentosan polysulfates, or a pharmaceutically acceptable solvate of one of these pentosan polysulfates. In the formula, each R represents a hydrogen atom, -COCH3 or -SO3X, and at least one R represents -SO3X； X represents a hydrogen atom, or a monovalent or divalent metal； X represents a hydrogen atom, or a monovalent or divalent metal； and n represents an integer of from 1 to 30 (inclusive). The present invention also provides a method for producing a pentosan polysulfate, which sequentially comprises a step for obtaining a neutral xylo-oligosaccharide by depolymerizing a plant-derived starting material and a sulfation step of the neutral xylo-oligosaccharide in this order.
