A solution of precursor of a pyroelectric material, e.g. BaSrTiO.sub.3, is coated on a surface of a silicon wafer having an array of mesas corresponding to infrared sensor elements to be formed thereon, and the pyroelectric material precursor coating is dried and then is subjected to a heat treatment for converting thereof into a pyroelectric thin film (sol-gel process). The internal stress in the pyroelectric thin film formed as thick as 1 .mu.m by repeating the process concentrates in the region (groove) between the mesas, hence cracks occurring in the film in connection with the stress are limited within the region and the portions of the film on the mesas can be free from the cracks. The pyroelectric thin film in the groove is selectively removed. An infrared image sensing device comprising sensor elements of uniform characteristics and high reliability is provided.