1. A brain information output apparatus, comprising: an intention determination information storage unit in which two or more pieces of intention determination information can be stored, each intention determination information including a pair of an intention identifier that is information for identifying an intention of a user, and a learning feature amount group including one or more feature amounts extracted from second learning data that is obtained by converting first learning data into intracerebral brain activity data, the first leaning data being data of a brain activity acquired from the outside of the cranium of a user when the user performs a trial, which is a series of actions, according to an intention identified by the intention identifier; a first brain activity data acquiring unit that acquires first brain activity data, which is data of a brain activity, from the outside of the cranium of a user; a second brain activity data acquiring unit that converts the first brain activity data acquired from the outside of the cranium of a user to intracerebral brain activity data, and acquires second brain activity data; a feature amount group acquiring unit that acquires, from the second brain activity data, an input feature amount group including one or more feature amounts; an intention identifier acquiring unit that acquires an intention identifier corresponding to the input feature amount group based on the two or more pieces of intention determination information stored in the intention determination information storage unit; and an intention identifier output unit that outputs the intention identifier acquired by the intention identifier acquiring unit.