This study investigated posttraumatic stress symptoms and posttraumatic growth among 534 fire fighters who were dispatched to the disaster area following the Great East Japan Earthquake. Specifically, we investigated the effect of acute stress symptoms and social support from peers and family on posttraumatic stress symptoms, depression, and posttraumatic growth one year after being dispatched. We found that dispatched fire fighters experienced posttraumatic growth as well as posttraumatic stress symptoms following disaster work. Moreover, social support from peers was positively associated with professional growth as a disaster worker, whereas social support from family positively associated with gratitude. These results imply that it is useful to take into consideration supporting the posttraumatic growth of fire fighters as an opportunity for professional growth with respect to stress management programs as well as relieving posttraumatic symptoms with early intervention.