A heat/acoustic wave conversion component includes a partition wall that defines a plurality of cells extending from a first end face to a second end face, and has a cell hydraulic diameter HD of 0.4 mm or less, an end face open frontal area of 60% or more and 93% or less, and heat capacity per unit length in the extending direction that tends to decrease with distance from the first end face. A first end portion on the first end face side that accounts for a region of 10% of a total length of the heat/acoustic wave conversion component has 1.1 times or more the heat capacity of that of a second end portion on the second end face side that accounts for a region of 10% of the total length.