This is the centre of attention of the building due to its size and height; it rises above the line of the main façade. Built in the 14th-15th Centuries, it is adjacent to the church and next to the plaza of the monastery. It is a construction with a rectangular floor plan. The central part of each face is built from masonry, with chains of ashlar on the corners. Mouldings are used to divide the tower up into four bodies; the uppermost body is topped off with battlements, which house the bells. The roof is constructed from solid bricks on ogival arches. This tower is characteristic of medieval fortifications.
The area on the ground floor was transformed into a sacristy. By the end of the 17th Century, its roof had been decorated with white and blue sgraffito. A ceramic panel dedicated to St. Jerome can be found on the first floor, showing three of the emblems that identify the saint: the cave, the lion and the cardinal's biretta. Alongside these appear other symbols that are more related to the order: a book, a mapa mundi and a squadron. The top floor houses the bells and has four ogival openings, one on each side.
The tower was the place chosen to place the foundation stone. The stone is carved in Gothic letters and reads:
“The Very Highest Lord Don Alfonso, son of the Infant Don Pedro, Duke of Gandia, Marquis of Villena, Count of Ribagorza and Denia, founded this monastery in the honour of God and St. Jerome in the year MCCCLXXXVIII”.