Maduro, who showed a photo of a white-plaster wall with marks that appear like eyes and a nose, said Chavez's face had briefly appeared to workers building a new subway line in Caracas in the middle of the night.
Speaking on state television, the president said: "My hair stands on end just telling you about it. Who is that face? That gaze is the gaze of the fatherland that is everywhere around us, including in inexplicable phenomena."
Maduro - who was elected president in April after the death of Chavez - has previously spoken of seeing the spirit of his idol several times, including in the shape of a bird.