assembly hall; chamber; the House
Refers to the physical meeting place of a legislative body, such as a parliament or congress. Often used in political news.
議員たちは議場に入った。
The lawmakers entered the assembly hall.
The lawmakers entered the chamber and took their seats.
議場では激しい議論が交わされた。
A heated debate took place on the floor of the House.
Opposition lawmakers occupied the chamber in protest.
The chamber erupted into an uproar over the Prime Minister's remark.
Some lawmakers walked out of the chamber in protest.
議事堂 refers to the whole building housing a legislature (e.g. the Diet Building), whereas 議場 refers specifically to the chamber room inside where debates and votes take place.
会議場 looks nearly identical to 議場 but means a general convention or conference hall, while 議場 specifically denotes a legislative assembly chamber.
conference room; assembly hall; meeting place
Compound of 議 (discussion, deliberation) and 場 (place, location).