Slovenian army spokesman Simon Korez said that the man, who worked as a military driving instructor in the northeastern town of Slovenj Gradec, was found dead at his home.
Korez said the man was though to have shot himself with a rifle, which was however not military issued.
According to the 24ur.com news site, the man took his own life on Wednesday afternoon after having recently returned from psychiatric treatment.
The incident comes only a day after a 27-year-old soldier shot herself while on duty as part of the Slovenian peacekeeping mission to Kosovo on Tuesday.
Korez had said that was the first suicide in the army ranks in five years.
