A text protection device for de-interlacing operation includes a pixel value difference calculation unit, a text detection unit and a vertical interpolation unit. The pixel value difference calculation unit is utilized for calculating pixel value differences of a plurality of pixels of a field according to a position of a target pixel being inserted into the field. The plurality of pixels forms a detection area corresponding to the target pixel. The text detection unit is utilized for determining whether the detection area includes a text stroke and determining whether the target pixel is located within a range of the text stroke to generate a text detection signal. The vertical interpolation unit performs a vertical interpolation operation to generate a pixel value of the target pixel according to the text detection signal.