An MPEG decoder for caption display, and a decoding method for caption display are provided. The MPEG decoder demultiplexes an external-applied MPEG stream into an audio stream and a video stream and decodes the video stream and outputs the decoded video stream on a screen. The decoder includes a video decoder for decoding the video stream and extracting user data from the header information of the video stream. A header memory stores the user data. A central processing unit (CPU) produces caption data by decoding the user data and transforming the caption data into on-screen-display (OSD) object data. An OSD controller for transforms the OSD object data into pixel data in response to a predetermined enable signal and outputs the pixel data. A video mixer mixes the pixel data with the decoded video data. In this way, caption data is produced by extracting user information from the header of an MPEG video stream and decoding the user information. The caption data is transformed into OSD data using OSD modules, so that ordinary televisions can perform a caption function.