a plain bearing unit is provided in which a sliding member made of thermoplastics having high recyclability and not containing solid lubricant provides low frictional coefficient and improves wear resistance even under circumstances where oil or grease cannot be used . a rotating , and / or swinging and / or reciprocating plain bearing unit includes a bearing made of resin containing glass and / or a carbon material ; a shaft ; and a gas supply portion adapted to supply dry gas subjected to dust removal to a bearing sliding portion where the bearing portion and the shaft slide with each other .