The present paper outlines a theoretical analysis on the shrinkage due to spot heating of a rectangular carbon steel plate with finite size. Elastic calculation based on the plane-stress condition was conducted, with an assumption that a negative dilatation-K was situated at the heating point. For the convenience of analysis, the rectangular region was transformed into a unit-sized circle, with one-to-one correspondence of the points in the respective regions. Reasonable assumption of the magnitude of-K, which depends on the heating and cooling conditions, gave a satisfactory agreement between the calculated shrinkages and the measured ones, and the characteristics of shrinkages due to spot heating on a finite-sized plate was clearly demonstrated.