Intumescence injury is a physiological disorder characterized by abnormal outgrowth of epidermal and parenchymal cells on the adaxial and/or abaxial surfaces of leaves. The purpose of this study was to examine cultivar differences in the incidence of intumescence injury, the relation between different calcium (Ca) conditions and intumescence injury, and to investigate countermeasures against intumescence injury in tomatoes. We grew tomato plants under different Ca nutrient conditions and treated them under high relative humidity and low ultra-violet light conditions to investigate intumescence injury incidence. The degree of intumescence injury varied among different tomato cultivars under a normal Ca condition with 4.5 me·L⁻¹ of Ca. Intumescence occurred in cultivars that showed no injury incidence under the normal Ca condition when they were grown with a low Ca nutrient solution containing 0.5 or 2.5 me·L⁻¹ of Ca. Intumescence injury incidence decreased in cultivars that showed high incidence under the normal Ca condition when they were grown with a high Ca nutrient solution containing 9.5 or 24.5 me·L⁻¹ of Ca. The differences in the incidence of intumescence among cultivars was marked with different Ca nutrient solution concentrations. There was a negative correlation between the degree of intumescence injury and the Ca content in tomato shoots. Foliar spraying with Ca was found to reduce the incidence of intumescence injury. It was suggested that intumescence injury in tomatoes can be mitigated by using cultivars in which intumescence is less likely to occur, increasing the Ca concentration of shoots by providing more Ca nutrients to the plant, and spraying Ca solution directly on the leaves.