An iron-based sintered body includes a metal matrix and complex oxide particles contained in the metal matrix. When a main viewing field having an area of 176 µm × 226 µm is taken on a cross section of the iron-based sintered body and divided into a 5 × 5 array of 25 viewing fields each having an area of 35.2 µm × 45.2 µm, the complex oxide particles have an average equivalent circle diameter of from 0.3 µm to 2.5 µm inclusive, and a value obtained by dividing the total area of the 25 viewing fields by the total number of complex oxide particles present in the 25 viewing fields is from 10 µm 2 /particle to 1,000 µm 2 /particle inclusive. The number of viewing fields in which no complex oxide particle is present is 4 or less out of the 25 viewing fields.