Among children and teens aged 17 or younger, 1.6 per 100,000 killed themselves with guns in 2014, compared with 1.0 per 100,000 in 2007.
An average of 493 children died of gun-related suicides each year covered by the study, which was led by Katherine Fowler and Linda Dahlberg of the US Centers for Disease Control and Prevention and published in the online journal Pediatrics.
"Suicides are often impulsive in this age group, with previous findings indicating that many who attempt suicide spend 10 minutes or less deliberating," the research paper said.
All told, nearly 1,300 children in the United States age 17 or younger died of gunshot wounds each year, with boys accounting for the vast majority of the victims, according to the study.
For decades, gunshot wounds have ranked second behind car crashes as the leading cause of death from injuries for US children. But while car travel has become safer, gun fatalities have remained high in that age group, pediatric experts say.