The aim of this paper is to present the mechanism of the frequency dividing operation and the limit operating frequency in the peak current-mode control DC-DC converter considering the turn-off delay time. The peak current mode control has the higher stability and the responsiveness than the conventional voltage mode control. However, if the switching frequency is increased ignoring the turn-off delay time, it would become the frequency dividing operation that the switching frequency operates lower than the clock frequency at the certain frequency. In this operation, there is a problem that the switching loss increases and the high frequency switching drive is hindered. In this paper, we clarified the mechanism of the dividing frequency operation and derived the relationship between the turn-off delay time and the limit operating frequency. Also, we derived the relationship when the slope compensation is applied as well. As experimental results, when there is the turn-off delay time, it was confirmed that the limit operating frequency of the DC-DC converter was limited to lower as the duty ratio was lower and the slope ratio of the slope compensation is close to 1.0.