Ishii was born in Ichihara on 1 February 1967. After graduating from Juntendo University, he joined Japan Soccer League club NTT Kanto in 1989. He played many matches from first season. He moved to Sumitomo Metal (later Kashima Antlers) in 1991. In 1992, Japan Soccer League was folded and a new league, J1 League, was founded. In 1993, the club won the 2nd place J1 League and Emperor's Cup. However he could hardly play in the match from 1996. He moved to Avispa Fukuoka in 1998. He retired at the end of the 1998 season.
Managerial career
Kashima Antlers
After retirement, Ishii became a coach for Kashima Antlers in 1999. He served as mainly physical coach. In July 2015, manager Toninho Cerezo was sacked and Ishii became a new manager. He was the Japanese manager of the club for the first time in 21 years since Masakatsu Miyamoto in 1994 (Except caretaker Takashi Sekizuka in 1998 and 1999). In October, the club won the champions 2015 J.League Cup. In 2016, the club won the champions J1 League and qualify for 2016 Club World Cup. He was also elected J.League Manager of the Year. At Club World Cup, the club became the first Asian team to reach the Club World Cup final. In the final, after a 2–2 draw against European champions Real Madrid after 90 minutes, they were beaten 4–2 after extra time. However the club performance is bad in 2017, he was sacked in May 2017.
Omiya Ardija
In November in late in 2017 season, Ishii signed with Omiya Ardija (former NTT Kanto) where he began his playing career. Although he managed 3 matches, the club could not win the matches and was relegated to J2 League. He remained a manager in 2018 season and aimed to return to J1 League. However Ardija finished at 5th place in 2018 season and missed promotion to J1. He resigned at end of the 2018 season.[1]
The season ended with Ishii winning the first 'Double Treble' (a treble in two consecutive seasons) in Thai football history with a 2–0 Thai FA Cup Final win over Bangkok United on 28 May 2023, thus completing the domestic treble for the fifth time in the club’s history. [4]
Thailand
On 22 November 2023, Nualphan Lamsam, team manager of Thailand national team appointed Masatada Ishii to be the new head coach of Thailand national team. Ishii replaced Alexandré Pölking who was sacked earlier. Ishii became the second Japanese head coach of Thailand, following Akira Nishino, who served for two years from July 2019.
Management style
Tactic
Based on 4-4-2 formation, it is characterized by aggressive tactics that use high press and short counter to break through the center. During his time as Omiya Ardija, he made good use of Genki Omae, who had a lack of scoring ability and was unsuccessful in the previous year, leading him to the league's top scorer.