The developed implant movement (IM) checker was used to examine the effect of dental implant mobility of different implant geometry. For the available bone-space an appropriate implant diameter and implant length would be concerned for dental implantation. Fifty-four artificial dental implants were made of phosphorous bronze cylinder in different lengths and diameters. These implants were embedded in different stiffness of artificial implant surrounding materials, Rigolac®. For the same implant length, the IM score decreased inversely proportional as the implant diameter increased. For the same diameter, the IM score tended to decrease linearly as the implant length increased. However, the linear relationship between the IM score was broken at a certain implant length. This condition shifted toward to the shorter implant length as the implant diameter increased. When the implant length was longer than this length, the implant mobility remained constant.