The 1855 Ansei-edo earthquake was estimated to occur beneath Tokyo metropolitan area and the seismic intensity there was 6 upper. There are several studies on the hypocenter, the mechanism and the magnitude of the event, but are still unknown factors. No broadband source models which can simulate the seismic intensity in both the Tokyo metropolitan and regional area were proposed. In this study, we estimate the broadband source model and the strong ground motions including surface waves as well as S-waves by the forward modeling of the seismic intensity scale using the empirical Green's function method.
 The patterns of seismic intensity distribution of the 1855 Ansei-edo earthquake are not concentric due to complex structure under the Kanto district. Therefore we firstly calculate the seismic intensity of M5-6 earthquakes occurred beneath Tokyo metropolitan area using K-NET, KiK-net and JMA95-type strong motion records. The distribution of the seismic intensity of the Mw5.9 earthquake occurred in northwest of Chiba prefecture on July 23, 2005 agrees best with the patterns of seismic intensity distribution of the 1855 Ansei-edo earthquake. Then we estimate the broadband source models composed of strong motion generation areas SMGAs and background using three earthquakes including this earthquake (050723) as element events. We assume Mw7.1 and estimate locations and sizes of two SMGAs with the same stress drop by forward modeling of seismic intensity distribution. The rupture starting point is also estimated. The seismic intensity estimated using 050723 agrees best with the observed seismic intensity from Tokyo metropolitan area to 200 km far beyond Kanto district. In the best model we assume a high-angle reverse fault in northwest of Chiba prefecture as an intraplate earthquake of the Philippine Sea plate based on the F-net CMT solution and the depth distribution of the aftershocks of 050723 (Koketsu and Miyake, 2005). The estimated centroid depth of SMGAs is 60 km. The short period spectral level A is the estimated using three earthquakes as element events are almost the same. We also estimate the broadband source models assuming Mw7.0 and Mw7.2 using 050723. The A estimated assuming Mw of 7.0, 7.1 and 7.2 is almost the same and the seismic intensity distributions are similar to each other. This result means that A is the influential parameter to seismic intensity but Mw is not so much. The A of 6.8×10¹⁹ [Nm/s²] of the 1855 Mw7.0-7.2 Ansei-edo earthquake is larger than A derived from the M0-A relation for interplate earthquakes of the Pacific plate (Satoh, 2010) and is slightly smaller than that for intraplate earthquakes of the Pacific plate (Satoh, 2013). The absolute value of A is comparable to A estimated for 1923 MW7.9 Kanto earthquake (Satoh, 2016).
 Strong motions in the periods of 0.05 to 10 s at the engineering bedrock are calculated by the 1-D linear analysis from the strong motions estimated at the surface from the best broadband source model with Mw7.1 using 050723. The strong motions at the surface are estimated using the revised equivalent linear analysis code DYNEQ by Yoshida. The pseudo velocity response spectra of east-west component at the engineering bedrock at Chiba, Otemachi and Shinjuku are slightly larger than those estimated for the 1923 Kanto earthquake (Satoh, 2016) in the periods of 0.6 to 2 s and the building standard law notification spectrum for the level-2 ground motion in the periods of 1 to 2 s. The peak ground velocities at the engineering bedrock at three stations are comparable to those during the 1923 Kanto earthquake, but the velocity pulses with periods of 1 to 2 s are more predominant than those during the 1923 Kanto earthquake.