A person who votes or is eligible to vote in an election or poll.
投票者は投票所で一票を投じます。
Voters cast their ballots at the polling station.
The number of young voters is increasing.
投票者 refers to someone who actually casts a vote, while 有権者 refers to anyone eligible to vote, whether or not they do so.
Compound of 投票 (tōhyō, 'voting') + 者 (sha, 'person').