An apparatus and method for non-destructively diagnosing crop growth using terahertz waves are provided. The apparatus includes an information extractor configured to extract status information on a crop from information on an image of the crop taken using terahertz waves, a database configured to store growth-stage-specific information on the crop, and a status determiner configured to compare the status information on the crop extracted by the information extractor with the growth-stage-specific information stored in the database, and determine the degree of growth of the crop.