<p>The Mikawa earthquake (M=6.8) occurred on January 13th in 1945, which was about one month after the Tonankai earthquake (M=7.9) and was in the midst of the Second World War. The Nk value is defined as the number of the totally collapsed wooden houses divided by the number of the death tool to discuss the characteristics of damages from the Mikawa earthquake. The average of Nk values is estimated to be about 10 for the 10 disaster inland earthquakes from 1891 to 1995 in Japan. The Nk value from the Mikawa earthquake shows 3.1, which is meaningfully small compared with other inland events. In this paper, causes of the small Nk value of the Mikawa earthquake are discussed. An influence of the evacuation in group for school children and teachers under the war can be estimated to be 0.4. Without this influence, Nk becomes 3.5, which is still small compared with the average. Influences of the occurrence shortly after the Tonankai earthquake and of the occurrence at midnight in winter were also considered to reduce the Nk value, though they cannot be quantified. On the other hand, it is found that Nk values show smaller tendency in the communities including the trace of the earthquake fault than those in the other municipalities. We examine the detail locations of totally collapsed wooden houses and death toll in Kota Village and the Katahara Town, where the surface fault breaks clearly appeared on the Fukozu fault. It was found that the Ichiba area of Koda Village and the northern Katahara Town in the vicinity of the Fukozu Fault show especially small, that are Nk=1.2 and 1.1, respectively. In these areas, large vertical displacements with more than 100cm can be found at many points along the Fukozu fault. It may be concluded that one of the highly probable causes of small Nk value near the earthquake fault is the influence of the occurrence of many cracks and inclination of ground accompanied by the surface fault break on addition to the extremely strong ground motion. In these situations, houses may be suddenly collapsed and people cannot avoid the risk of death easily.</p>