Ilmajoki (Finnish pronunciation:[ˈilmɑjoki], Swedish:Ilmola[ilmolɑ]) is a municipality of Finland.
It is located in the province of Western Finland and is part of the Southern Ostrobothnia region. The population of Ilmajoki is 12,181 (30 June 2015) and the municipality covers an area of 576.79km (222.70sqmi) of which 2.90km (1.12sqmi) is inland water (1 January 2011). The population density is 21.12/km (54.7/sqmi).