The pyroelectric coefficient under the applied DC-bias field consists of two terms: (i) induced pyroelectric coefficient, (ii) intrinsic (true) pyroelectric coefficient. From the dielectric/pyroelectric data of both the unsubstituted (Ba, Sr)TiO3 (BST; with Ba: Sr = 2:1) and the Zr-substituted BST, it was shown that the intrinsic pyroelectric coefficient made a dominant contribution to the net pyroelectric coefficient below the Curie temperature (Tc). On the other hand, the induced pyroelectric coefficient contributes significantly to the net pyroelectric response above Tc by virtue of the reduction in the temperature-dependent spontaneous polarization. The behavior of the induced pyroelectric response for the Zr-substituted BST was further analyzed using a semiempirical model based on the concept of a Gaussian distribution of the local Curie points. The two practically important figures-of-merit (Fv and FD) under various DC-bias fields were estimated as a function of temperature. An optimum condition of the composition for the thermostability of pyroelectric figure-of-merit at near ambient temperature was deduced from the analysis, and it was 10 at. % Zr-substitution with Ba: Sr = 3:1 (i.e., Ba0.75Sr0.25Ti0.9Zr0.1O3).