The rate of absorbed Ca to N was less than half of Enshi or Hoagland solution in tomato (Solanum lycopersicum Mill.) grown with restricted root zone volume in previous experiments. Tomato plants were grown in plastic pots containing 250 or 500ml of peat based medium with modified Enshi solutions containing 1, 2 or 4mM of Ca. The solutions were prepared by replacing a part of Ca(NO3)2・4H2O to NH4NO3. Although Ca concentration was higher than 2mM in drainage collected from plants supplied 1mM Ca solution, absorbed amount of Ca was very small and severe symptom of Ca deficiency was observed. Incidence of blossom-end rot (BER) increased with decrease in Ca concentration of the solution and yield decreased to 50% and 36% of 4mM control, in 2mM and 1mM plots, respectively. Among fractionated Ca in stem of lateral shoot, decrease in water-soluble fraction was remarkable compared to 1N NaCl- or 0.6N HCl-soluble fractions. Tomato plants were then grown with modified solutions containing 1~4mM of Ca and fractionated Ca was determined for distal half of fruits. With decrease in solution Ca, fruit Ca decreased in all fractions, and days to BER incidence after flowering also decreased. Significant relationship was found only between the water-soluble Ca concentration in fruit tissue and rate of BER incidence. Thus water-soluble Ca in tomato fruit may closely relate to BER incidence, and an efficient tool to estimate the potential risk of BER may possibly be developed by determining the Ca fraction in the stem of lateral shoots.