PURPOSE: To provide a shaft seal which can prevent leakage of lubricant from a bearing and mixing of foreign object into the lubricant from the environment.

CONSTITUTION: A labyrinth type seal assembly 10 holds adjusted porosity elements 26, 28 in a labyrinth passage between rotary seal elements. The adjusted porosity elements are preferably made of open celled foaming materials such as polyurethane. The adjusted porosity elements promote the prevention of entry of contamination including solid or liquid substance, loss of shield materials and flooding in a drain port.