An apparatus and method determine a dielectric access in a portable terminal. The method includes generating a TX signal of a specific frequency band by performing frequency conversion, modulation, and digital/analog conversion. The method also includes detecting the power of the TX signal and converting the detected power using Analog-to-Digital Conversion (ADC). The method further includes loading an ADC table defining values for determining the approach/withdrawal of a dielectric to/from the portable terminal, and comparing the power of the TX signal and the ADC table to determine the approach/withdrawal of a dielectric to/from the portable terminal.