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 mutually converts heat exchanged between the partition wall and the working fluid and energy of acoustic waves resulting from oscillations of the working fluid. Hydraulic diameter HD of the heat/acoustic wave conversion component is 0.4 mm or less, where the hydraulic diameter HD is defined as HD=4×S/C, where S denotes an area of a cross-section of each cell perpendicular to the cell extending direction and C denotes a perimeter of the cross section. The heat/acoustic wave conversion component has an open frontal area at each end face of 60% or more and 93% or less. The partition wall has arithmetic surface roughness (Ra) at the surface of 3 μm or more and 20 μm or less.