An analog-digital converter that includes voltage acquisition circuitry that acquires a voltage value of an analog signal in a settling period, calculation circuitry that calculates a predicted convergence voltage value of the analog signal based on the voltage value of the acquired analog signal, reference signal generation circuitry that generates a ramp wave reference signal based on the predicted convergence voltage value, comparison circuitry that compares the voltage value of the analog signal with the ramp wave, measurement circuitry that measures a time period from a generation of the reference signal to a time before the voltage value of the analog signal intersects with the ramp wave of the reference signal, and addition circuitry that derives a convergence voltage value of the analog signal by adding a voltage value corresponding to the measured time period and a voltage value based on the predicted convergence voltage value.