At the start of the 2004 season, Naldo joined Juventude and made his debut on 2 May 2004, coming on as a substitute, in a 4–0 win against Paraná Clube. He then received his first start for the club, in a 1–0 win against Coritiba on 10 July 2004. Seven days later on 17 July 2004, Naldo scored his first goal for the club from a free kick, in a 1–0 win against Flamengo. Two weeks later on 1 August 2004, he scored his second goal for Juventude, in a 1–1 draw against Vasco da Gama. Naldo helped the club kept four consecutive clean sheets in the next four matches between 5 August 2004 and 14 August 2004. He scored his third goal of the season, once again from a free kick, in a 2–1 loss against Santos on 1 September 2004. After missing several matches due to injury, Naldo scored on his return to the starting line–up against Athletico Paranaense on 7 October 2004. At the end of the 2004 season, having played alongside Thiago Silva, he went on to make twenty–five appearances and scoring four times in all competitions.