The purpose of this study was to clarify the kinetic features of the trunk under different hitting-point height conditions (high, middle, and low) in baseball tee-batting. Twenty-three collegiate male baseball players (age: 19.8±1.3 yr, height: 1.74±0.04 m, whole-body mass: 74.1±6.2 kg, athletic career: 12.0±2.1 yr) participated. Three-dimensional coordinate data were captured using a VICON-MX system (12 cameras, 250 Hz), and kinetic data for the individual hands were collected using an instrumented bat equipped with 28 strain gauges (1000 Hz). Three kinds of tee-batting heights were set for each participant based on the upper and lower limits of the strike zone according to the baseball rule. The torso was modeled with the rigid upper and lower trunk segments connected by a torso joint with three axes: the ante/retro flexion, right/left lateral flexion, and right/left rotation axes. Kinetic variables, e.g. joint force and torque, mechanical power, and mechanical work, were obtained by inverse dynamic calculation. These data were expressed for a right-handed batter and normalized by the time of the forward swing from the swing start to the ball impact as 0-100%, and the time was divided into down-swing and level-swing phases in order to evaluate the mechanical work. From the last half of down-swing phase until ball impact, the retroflexion torque under the low condition was significantly larger than those under other conditions. The left rotation torque and positive torque power showed particularly large values in the level-swing phase regardless of the hitting-point height. The mechanical energy flow generated by the torso joint torque showed inflow from the lower trunk to the upper trunk, and outflow from the upper trunk to the individual upper arms regardless of the height condition over the forward swing. In addition, there were significant positive correlations between the positive mechanical work done by the joint torque about the right/left rotation axis and the maximum bat-head speed during the level-swing phase under the middle and low conditions. These results indicate that 1) the ante/retro flexion axis torque is needed to maintain the configuration of the upper trunk against the large centrifugal force exerted along the bat around the moment of ball impact, 2) the right/left rotation axis torque contributes to the generation of the large mechanical energy, the transfer of energy to the upper limbs, and the generation of the bat-head speed regardless of the height condition.