A transfer clock converter for digital data of the present invention is a circuit for converting digital data synchronized with a first transfer clock into digital data synchronized with a second transfer clock and outputting the digital data, and includes a plurality of latching elements and a comparator-selector circuit. The comparator-selector circuit compares the output data from predetermined latching elements, selects output data to be output according to the result of the comparison, and outputs the selected output data. With this structure, it is possible to always output correct digital data without using a PLL circuit or the like, thereby significantly improving the reliability.