Albirex Niigata Tanaka was educated at and played for Maebashi Ikuei High School in
Maebashi,
Gunma. While he was a high school student, he was registered as a
J.League specially-designated player by
Albirex Niigata. It meant that he was eligible to play and train with
Albirex Niigata, while he was still eligible to play for his high school football club. He played two league games for Albirex in the 2005 season. He made his debut on 27 November 2005 in a
J1 League away match against
Nagoya Grampus Eight. After graduating from his high school in 2006, he officially signed with Albirex Niigata. His first appearance as a professional player came on 5 March 2006 in a league match against
Kawasaki Frontale. His first professional goal came on 8 April 2006 in a league match against
Ventforet Kofu.
HJK Helsinki After scoring once in five matches for his new team
HJK Helsinki in the
2015 Finnish League Cup, he scored on his
Veikkausliiga debut against
RoPS in a 3–1 away win on 12 April. In October 2015 of the same year, HJK exercised their option of keeping Tanaka under contract for the 2016 season. Tanaka was voted as a best eleven member in 2015 and 2016 in the Finnish League. On 25 October 2017, it was announced that Tanaka would leave HJK at the end of the
2017 season.
Cerezo Osaka He is playing for
Cerezo Osaka for the 2018 season.
Return to HJK On 3 March 2020, Tanaka returned to
Helsingin Jalkapalloklubi, after signing a contract until the end of July. In the
2023 season Atom surpassed the 200th match mark in HJK. On 28 November 2023, Atom extended his contract with HJK, signing a new deal for the
2024 season, which will be his eight season with the club in total. In December 2024, it was announced that Tanaka would leave HJK after the 2024 season.
KTP In January 2025, Tanaka signed with newly promoted Veikkausliiga club
Kotkan Työväen Palloilijat (KTP). ==International career==