Who needs a police certificate?
In general, you and everyone in your family who is 18 years of age or over (16 years of age in certain jurisdictions) need to obtain a police certificate. You must obtain a police certificate from each country or territory where you have lived for six consecutive months or longer since reaching the age of 18.
The certificate must have been issued no more than three months before you submit your application.
FBIから無犯罪証明の取り方は、下記になります。
http://www.cic.gc.ca/english/information/security/police-cert/north-america/united-states.asp