The present invention provides an earthquake damage spread reducing method and an earthquake damage spread reducing system, for use in a semiconductor manufacturing apparatus, which can predict occurrence of an earthquake and prevent fall down of a boat, thus minimizing damage of the earthquake. An earthquake damage spread reducing system 27 includes a receiving unit 28 for receiving urgent earthquake information, based on preliminary tremors, to be distributed via a communication network 26 , or alternatively, includes a preliminary tremors detection unit 60 for directly detecting the preliminary tremors. A control unit 29 performs a first step of stopping the operation of a semiconductor manufacturing apparatus 1 , based on the urgent earthquake information to be received or on the preliminary tremors to be detected, as well as performs a second step of holding a boat 4 , in a contact or non-contact state, in order to prevent fall down of the boat 4 , in which objects to be processed are loaded in a multistage fashion.