In this paper, we consider time-of-arriaval (TOA) estimation based on energy detection of time hoppingultra wideband-impulse radio (TH-UWB-IR) signals. The accuracy of TOA estimation is largely degraded in the presence of strong multiuser interference (MUI) and intersymbol interference (ISI). As methods to mitigate the effects of MUI and ISI on TOA estimation, applying filter to the received signal energy is shown to be effective. As filters, minimum filter and median filter have been applied to TH-UWB-IR. However, anything other than the two filters has not been reported. It has not also been clarified where and what filter we should use in the TOA estimation. In this paper, we evaluate the TOA estimation accuracy of TH-UWB-IR system with the following filters: median filter, minimum filter, and outlier filter. We clarify where we apply each filter in the TOA estimation.