A time-to-digital converter and a converting method are provided. The time-to-digital converter includes: a phase locked loop unit configured to multiply an input reference clock by using a phase locked loop (PLL); a counting unit configured to count the multiplied input reference clock and record an edge position of an input signal; a delay locked loop unit configured to decompose the multiplied input reference clock into a multi-phase clock using a delay locked loop (DLL), and sense the recorded edge position of the input signal among the decomposed multi-phase clock and record a fine edge position; and a control unit configured to calculate a time difference in time of flight (ToF) between a start signal and a stop signal of the input signal by using the recorded edge position and the recorded fine edge position.