In 2021, it was reported that SHI has ceased making light machine guns for the JSDF, citing a bleak economic prospects in the arms sector.

[7] In May 2005, the JFTC filed criminal charges with the Public Prosecutor’s Office for violations of the Antimonopoly Act against Sumitomo Heavy Industries and seven other companies for engaging in collusion in the bidding process for bridge construction projects commissioned by the former Japan Highway Public Corporation and the Ministry of Land, Infrastructure, Transport and Tourism (see ja:橋梁談合事件).

On June 12, 2006, the Osaka District Public Prosecutors Office Special Investigation Department indicted Sumitomo Heavy Industries and ten other companies for colluding in the construction of sewage and sludge treatment facilities commissioned by local governments, violating the Antimonopoly Act.

[15] On January 7, 2020, a former secretary of the Sumitomo Heavy Industries Labor Union was arrested on suspicion of embezzling ¥50 million from a retirement savings account.

[18] On May 20, 2021, Sumitomo Heavy Industries revealed that design drawings for sample parts used in test machine guns for the Japan Ground Self-Defense Force had been leaked to China.