Pietro De Martino or Di Martino (31 May 1707 – 28 January 1746) was an Italian mathematician and astronomer.^[1]

Born in Faicchio, he was brother of Angelo, professor first of medical physics then of mathematics at the University of Naples; and of Nicola Antonio De Martino, professor di mathematics and director of the Real Corpo degli Ingegneri (Royal Engineers Corp) and Marine Guard. Pietro De Martino was a pupil of Agostino Ariani and of Giacinto De Cristoforo (1650-1730). In 1735 he was assigned of the astronomical and nautical chair at the University of Naples.^[2]

He disputed with Roger Joseph Boscovich on the question if it is possible to gain a right result starting from a wrong hypothesis.^[1]

He authored various works; his Nuove istituzioni di aritmetica pratica, published originally in 1739 in Naples, had many reprints (the better known of the 1758; one also in Turin in 1762).^[1] He died in Naples in 1746.^[2]

• Degli elementi della geometria piana composti da Euclide Megarese, e tradotti in italiano, ed illustrati (in Italian). Naples: Alessio Pellecchia. 1785 [1736].
• Philosophiae naturalis institutionum libri tres (in Latin). Naples: Felice Carlo Mosca. 1738.
• Nuove istituzioni di aritmetica pratica (in Italian). Naples: Felice Carlo Mosca. 1739.
• Nuove instituzioni di aritmetica pratica (in Italian). Turin: Stamperia Reale. 1762 [1739].
• De luminis refractione et motu (in Latin). Naples. 1740.
• De corporum quae moventur viribus, earumque aestimandarum ratione (in Latin). Naples: Felice Mosca. 1741.