A memory device, an error correction device and an error correction method thereof are provided. The error correction device includes a first error correction decoder and a second error correction decoder. The first error correction decoder performs at least one iteration of a first error correction operation on a data chunk, calculates a counting number of syndrome values equal to a set logic value generated in the at least one iteration of the first error correction operation, and generates a control signal according to the counting number. The second error correction decoder receives the control signal and determines whether to be activated to perform a second error correction operation on the data chunk or not according to the control signal. An error correction ability of the second error correction decoder is higher than an error correction ability of the first error correction decoder.