noun
Refers to the person or entity that plans and runs an event, conference, or competition. Can imply both organizational and financial backing.
大会の主催者は地元の企業です。
The organizer of the tournament is a local company.
主催者側の都合でイベントが中止になった。
The event was canceled due to circumstances on the organizer's side.
企画者 emphasizes planning and devising, while 主催者 includes the actual execution and hosting of the event.
Compound of 主催 (shusai, 'sponsorship, organization') + 者 (sha, 'person').