Abstract: A hammer system for automatically carrying out a standard penetration test is disclosed. A cylindrical housing, in which an anvil coupled to a drill rod is received, is supported by a first hydraulic cylinder coupled to boring equipment. A cylindrical hammer is received in the housing. The hammer includes a holding assembly therein, which selectively holds and raises the hammer by a second hydraulic cylinder. Element for limiting a stroke of the hammer is spacedly connected to the holding assembly to be raised and lowered therewith. The limiting element includes a first sensor to detect a slot formed at the housing when the hammer is raised, thereby counting the number of blows. The hammer includes a plurality of protrusions on its outer surface. A wall of the housing includes a second sensor to detect the number of protrusions passed over the second sensor when the hammer is raised, thereby calculating a penetration depth from a difference between the numbers of protrusions detected for two continuous blows.