Patent ID: 7913988

Claim:
A crease forming apparatus for forming a crease along a given line in a recording member, comprising: a crease forming member that extends along the given line of the recording member for forming the crease in the given line of the recording member; an insertion groove that is formed in a portion disposed opposed to the crease forming member and that allows insertion of the crease forming member thereinto; hold members that are disposed with the crease forming member therebetween and that holds the recording member from both sides of the recording member with respect to the given line in a state (i) where the given line of the recording member is set between the crease forming member and the insertion groove and (ii) where the recording member is situated at a wait position in which the leading end of the crease forming member does not project from the position of the recording member; and a drive unit that drives the crease forming member in such a manner that the crease forming member advances and retreats between the wait position and a crease forming position for forming the crease in the recording member, and that, in a state where the recording member is held by the hold members, inserts the crease forming member situated at the wait position into the insertion groove up to the crease forming position against the holding force to the recording member by the hold members in such a manner that a peripheral portion of the given line of the recording member is set along the crease forming member, wherein the insertion groove does not include a contact surface, when the crease forming member is inserted to the crease forming position, that holds the crease leading end of the recording member with the leading end of the crease forming member.