This study investigates the collapse and survival factors of two adjacent stone arch bridges, the Futamata and Futamata-Fukura bridges, during the 2016 Kumamoto earthquake. Despite their similar construction period and dimensions, the Futamata Bridge remained intact, whereas the Futamata-Fukura Bridge suffered significant damage, leading to its partial collapse. To understand the cause of this discrepancy, microtremor measurements are conducted to estimate the natural frequencies of both bridges and the predominant frequencies of the ground supporting their foundations. In addition, the earthquake ground motion at the bridge site is estimated using an empirical method based on the microtremor horizontal-to-vertical spectral ratio. The results indicate that the Futamata-Fukura Bridge experienced higher peak ground acceleration and a larger acceleration response than the Futamata Bridge as a result of its orientation relative to the earthquake motion. The estimated acceleration response spectra further suggest that the acceleration at the pre-earthquake natural frequency of the Futamata-Fukura Bridge was even higher than the post-repair value of 5 Hz, contributing to its collapse.