This study aimed to clarify the biomechanical characteristics of preparatory motions required for defensive diving by soccer goalkeepers (GKs). Seventeen collegiate male GKs and 14 collegiate male outfield players (strikers) participated. The experimental setup was based on a previous study (Numazu et al., 2019), and the experiment was conducted using simulated shooting situations in the penalty area. Three-dimensional coordinate data for the GKs and strikers were captured using 2 motion capture systems with 24 cameras (250 Hz, 16 cameras for the GKs and 8 cameras for the strikers). The 2 systems were synchronized by an analog signal (1000 Hz). We analyzed 430 trials where the GKs dived toward the shot (NU: 75 trials, NM: 94 trials, NL: 37 trials, FU: 58 trials, FM: 83 trials, and FL: 83 trials). The participating GKs performed a small jumping motion vertically upward, similar to a split-step, as a preparatory motion. The primary variables computed were as follows: elapsed time of preparatory motion, velocity of the center of gravity at takeoff in the frontal plane, stance width divided by leg length, height of preparatory motion, segment angle of the trunk in the sagittal plane, and angles of the lower limb joints. The major findings were as follows: 1) To respond quickly to the shot, the GKs leaned the trunk forward and flexed the lower leg joints, externally rotated the hip joints of both legs, abducted the hip joints, and opened the feet to 70% of the leg length. 2) GKs performed the take-off of the preparatory motion simultaneously when the striker made contact between the support leg and the ground. 3) It was considered that GKs changed their movement to match the flight trajectory of the ball later than CSon.