博伊西县（Boise County, Idaho）是美国爱达荷州西部的一个县。面积4,938平方公里。根据美国2000年人口普查，共有人口7,535。县治爱达荷城 (Idaho City)。

成立于1864年2月4日。县名来自博伊西河 (意思是森林地)。

Boise County is a rural mountain county in the U.S. state of Idaho. As of the 2010 census, the population was 7,028. The county seat is Idaho City, and Horseshoe Bend is its largest city.

Boise County is part of the Boise, ID Metropolitan Statistical Area.