  Hyperfine induced $2s2p~^3P_0 \rightarrow 2s^2~^1S_0$ transition rates in an
external magnetic field for Be-like $^{47}$Ti were calculated based on the
multiconfiguration Dirac-Fock method. It was found that the transition
probability is dependent on the magnetic quantum number $M_F$ of the excited
state, even in the weak field. The present investigation clarified that the
difference of the hyperfine induced transition rate of Be-like Ti ions between
experiment [Schippers {\sl et al.}, Phys Rev Lett {\bf 98}, (2007) 033001(4)]
and theory does not result from the influence of external magnetic field.
