Abstract: A slope indicator for fastening to the ground of a putting green to indicate the slope during the game of golf is disclosed to include a housing having a transparent top face and a pointed bottom anchoring rod for fastening to the ground, a fluid sealed in the housing, and a bubble formed in the fluid inside the housing and shifted in the fluid subject to the tilting condition of the housing to give an indication of the slope of the ground to which the slope indicator is fastened.