thumb|right|150px|Blason des Candiano.
'''Pietro IV Candiano''' est le 22 doge de Venise élu en 959. 

==Biographie==
Pietro Candiano est le fils ainé de Pietro III Candiano auquel il succède en 959.

=== La conquête du pouvoir ===
Son père, le doge Pietro III Candiano, l'avait fait élire co-régent: l'intention étant que le fils succède au père avec l'espoir que le titre devienne héréditaire. L'ambition personnelle de  Pietro IV le conduit à s'opposer à une grande partie des Vénitiens, au point que lors d'une assemblée populaire, le doge, son père, réussit à le sauver d'une mort certaine seulement en l'exilant. Pietro IV quitte alors Venise suivi de quelques fidèles et se rend auprès du marquis Guido qui le conduit à la cour de son père, le roi d'Italie Bérenger II. Pietro participe avec Guido à une expédition contre Teobaldo marquis de Spoleto, et à son retour, il obtient le soutien de Berenger pour attaquer Venise. À la tête de quelques partisans, il destitue son père et se nomme doge.

== Dogat ==
Parmi ses premiers actes, il fait aveugler et expulser l'évêque de lombarde Waldrada, parente de l'empereur d'occident Otton , en empireur d'orient: Le Byzantin Jean  menace de rétorsions si les Vénitiens ne cessent leur contrebande avec les Sarrasin pendant les guerres qui les opposent ce que le doge accepte (971).

'''Pietro IV Candiano''' (died 976) was the twenty-second (traditional) or twentieth (historical) Doge of Venice from 959 to his death. He was the eldest son of Pietro III Candiano, with whom he co-reigned and whom he was elected to succeed. 

==Rise==
By associated his son with him in the dogeship, Pietro III was trying to establish a hereditary monarchy in Venice. This incurred the wrath of the people, who, in a popular assembly, tried to kill the doge. Pietro IV intervened to save his father's life and exiled him with a small group of followers to Margrave Guy took him to his father, the king of Italy, Berengar II. 

Pietro III then participated with Guy in an expedition against Theobald II, Duke of Spoleto, and gained the support of Berengar for an assault on Venice. At the head of a band of partisans, Pietro IV defeated his father, but did not kill him. He was then elected sole doge.

==Dogado==
One of his first acts as doge was the blinding and expulsion of the bishop of Castello, accused of simony. In June 960, he reconvened the popular assembly and had them approve of a law prohibiting the slave trade. 

For political reasons, Pietro repudiated his first wife, Joan, forcing her into the convent of Santa Zaccaria. He had had two children through her: his son Vitale was later elected doge and his daughter was married to Lombard Waldrada, daughter of Hubert, Duke of Spoleto, and a relative of the Emperor Otto I. As a relative also of the king of Italy, Waldrada brought him a large dowry including the possession of Treviso, Friuli, and Ferrara. 

On John I. John threatened war if the Venetians would not stop contrabanding with the Saracens against whom John was then battling fiercely on multiple fronts. In 971, Pietro had to consent to end the trade with the Moslems.