The Great East Japan Earthquake of 2011 had a serious psychological impact not only on residents, but also on public servants who worked for residents in prefectures and municipalities. Although public servants worked in highly stressful situations, disaster-related stress among them has not been studied, as has been the case for residents. We examine the stress trajectory of Ishinomaki public servants in Miyagi prefecture (N = 573; 317 men, 256 women), which was directly affected by the Great East Japan Earthquake, and analyse the effects of risk factors that included poor workplace communication, insufficient rest, having dead or missing family members, and living in a shelter. Six surveys were conducted (baseline approximately three months after the earthquake, and follow-up in approximately six-month intervals over a four-year period) using the Japanese version of the Kessler six-item Psychological Distress Scale. The analysis was conducted using five models, which included one for each risk factor and all four risk factors. Latent growth curve analysis indicated that stress response follows a cubic trajectory over four years. Psychological distress sharply reduced from 2011 to 2012 before stabilising and then slowly declining from 2014 to 2015. In the results of the analysis for each model, all risk factors affected stress response in the baseline. Individuals with poor levels of workplace communication experienced higher stress than those who had good levels of workplace communication. Our findings show that public servants' stress responses decrease with time, regardless of whether or not there are risk factors involved. These results suggest that workplace communication in daily life can prevent the deterioration of mental health since risk factors affect the baseline of stress response.