1. An electromechanical transducer element comprising: a lower electrode; an electromechanical transducer film; and an upper electrode, wherein the electromechanical transducer element is disposed on an oscillation film on a substrate, wherein the electromechanical transducer film is formed of lead (P) zirconate (Zr) titanate (Ti) (PZT), wherein a composition ratio of Ti in the electromechanical transducer film, defined as Ti/(Zr+Ti), is greater than or equal to 45% and less than or equal to 55%, and wherein, in a crystalline orientation of the electromechanical transducer film, for an orientation ratio of a (100) plane orientation calculated based on a ratio of a peak intensity value of each orientation when a total of the peak intensity values obtained by θ-2θ measurement of an X-ray diffraction method is set to be 1, Δρ(100) is less than or equal to 5%, wherein Δρ(100) is a gradient with respect to the (100) plane orientation in an array direction, and the ratio of each peak intensity value of each orientation is represented by ρ(hkl)=I(hkl)/ΣI(hkl), where ρ(hkl) is a degree of orientation in an (hkl) plane orientation, I(hkl) is the peak intensity value of the orientation, and ΣI(hkl) is the total of the peak intensity values.