The present invention discloses a conference system and an apparatus and a method for mapping participant information between heterogeneous conferences. The apparatus for mapping participant information according to one embodiment of the present disclosure includes: a first acquirer configured to acquire identification information of a first terminal accessing a first conference server; an accesshistory inquirer configured to inquire an access history database to extract access history information corresponding to the identification of the first terminal; a second acquirer configured to acquire one or more pieces of mapping candidate identification information from the extracted access history information; a selector configured to select a terminal corresponding to the mapping candidate identification information among one or more terminals accessing a second conference server as a second terminal; and a mapper configured to map identification information of the second terminal to theidentification information of the first terminal.