The layered transition metal dichalcogenides (TMDs) have raised considerable interest in the past decades for both fundamental physics and low-dimensional nanodevice applications. Recently, intriguing phenomena of Ising superconductivity and quantum metallic state have been reported in two-dimensional (2D) 4Ha-TaSe₂ nanodevices. Here, we report the magnetic field induced superconductor–metal transition (SMT) in mechanical exfoliated 4Ha-TaSe₂ nanodevices with thickness down to 2.5 nm. We observe the quantum Griffiths singularity (QGS) of SMT in thin 4Ha-TaSe₂ nanodevices by performing ultralow temperature transport measurements and activated scaling analysis. With increasing the thickness of TaSe₂ nanodevice to 10.6 nm, the signature of magnetoresistance crossing region can hardly be detected, revealing the thickness dependence of SMT. In this procedure, the disorder strength plays a dominant role. This work enriches the platform for studying QGS and may stimulate further investigations on the correlation between different novel quantum phenomena in the same 2D superconducting system.