Abstract: Device and method for converting a video format of a digital T.V. which can convert an SD video into an HD video, the device including a VLD for making a variable length decoding of a received bit stream to determine a received video source of being an SD video and provide a relevant signal according to a result of the determination, a detector for detecting existence of edge components of the SD image using inverse quantized DCT coefficients, and a format converter for interpolating and format converting an SD image data obtained by adding an IDCT SD image data and a motion compensated SD image data into an HD image data by applying an interpolation equation according to signal from the VLD and the detector, whereby distortion of the image and degradation of a picture quality are prevented.