The Mausoleum of Attar of Nishapur (; ) is a mausoleum, located west of Nishapur, in the northeastern province of Razavi Khorasan, Iran. The complex was built by the order of Ali-Shir Nava'i in the 15th century CE, during the Timurid era, and contains the tomb of Attar of Nishapur. It is located near the Mausoleum of Omar Khayyám.
The complex was added to the Iran National Heritage List on 9 December 1975, administered by the Cultural Heritage, Handicrafts and Tourism Organization of Iran.
The structure is octagonal in shape with a tile worked onion shaped dome. It has four entrances, the northern one is the main entrance. The structure is adorned with coloured (green, yellow and blue) tiles and carvings. The interior site is covered by plaster and has four seats. The mausoleum is located in a garden covering an area of approximately . The grave of the well known painter Kamal-ol-molk is also situated in a part of this garden.