1. An apparatus for determining whether or not a program violates a convention, the apparatus comprising: an input unit for receiving an input of a target program to be an object of a determination on whether to violate the convention; a violation storing unit for beforehand storing violation information indicating a structure of a program violating the convention; a converter for converting an abstract syntax tree of the target program to a conversion tree with a predetermined conversion rule; and a determination unit for determining that the target program violates the convention on condition that at least a part of a structure of the conversion tree agrees with the violation information.