To precisely estimate earthquake damage immediately after the occurrence of an earthquake and the number of men required for the restoration of the earthquake.

When earthquake damage occurs in a gas supply object area by a gas supplier, a house collapse rate based on a supply tube installation year and the size of the earthquake is accumulated as a database. When the earthquake newly occurs, the collapse number of the houses is estimated based on the distribution of the supply tube installation years in the area becoming the object where damage is to be estimated and the estimation value of the size of earthquake movement in respective areas, and the degree of damage can be judged. The number of men and the number of days, which are required for restoration against the house collapse rate, are previously obtained from results at the time of past earthquake as the database. The number of men, which is to be supplied and is required for restoration, can precisely be estimated from the house collapse rate at the time of new earthquake damage.