We present a concept of parametric delay-dispersion tuner (PDDT) that is capable of the continuous tuning of delay and dispersion for wideband optical signals in a simultaneous and independent manner. We experimentally demonstrate a tunable delay of 22 ns for 2.6 ps return-to-zero optical signals without distortion and error-free transmissions at 43 gigabits per second. We show that PDDT has a bandwidth of ~0.9 THz, resulting in the delay-bandwidth product of ~20,000, and exhibits an excellent performance in terms of stability and reproducibility.