Delijan County is in Markazi province, Iran. Its capital is the city of Delijan.

Markazi Province is one of the 31 provinces of Iran. The word markazi means "central" in Persian and the province lies in central Iran. The capital of the province is the city of Arak. At the time of the National Census of 2006, the province had a population of 1,326,826 in 364,155 households. The following census in 2011 counted 1,413,959 people in 426,613 households. In 2014 it was placed in Region 4. At the most recent census in 2016, the population had increased to 1,429,475 in 455,866 households. Persians make up the majority of the province, but there are significant minorities of Azerbaijanis, Kurds, Lurs, etc.