A state of emergency needs collaboration among government agencies. Regarding the response to emergency, collaboration among agencies has become important in the public sector. However, despite the necessity and the importance of collaboration in dealing with emergency, it is hard to produce successful collaboration among government agencies. Why is it hard to achieve effective interagency collaboration in emergency? And what do we miss to understand interagency collaboration in emergency? The paper addresses these questions from the perspective of organizational culture. The collaboration case between the New York City Police Department (NYPD) and the New York City Fire Department (FDNY) in response to 9/11 emergency in New York City is used to analyze the effects of each organizational culture on interagency collaboration. The analysis of the two organizations by organizational culture shows that NYPD has a more procedure-based organizational culture and FDNY has a more result-based organizational culture. The members of NYPD and FDNY made their decisions and activities responding to 9/11 emergency on the basis of each of organizational culture, which produces collaboration problems. The results of the study indicate that organizational culture should be considered and more diverse studies of organizational culture for effective interagency collaboration in emergency are needed.