Accidents involving metals brought into the MRI room are occurring with increasing frequency. The Japan Council for Quality Health Care has released medical safety information about bringing magnetic materials into the MRI room, showing that this is an important safety issue. In our hospital, there were 4 accidents involving metal brought into the MRI room between April 2012 and March 2016. One serious incident was a projectile accident involving scissors carried by a nurse. In response, we have adopted new preventive measures, including specialized uniforms and a color-coding scheme for indicating MRI-safe and MRI-unsafe items (using colored tape, etc.). Here we report on the effect of these accident prevention efforts.