© 2016 The Physical Society of Japan. The magnetization change ΔM at the superconducting transition of LaIrSi3 has been measured in various magnetic fields H. The observed ΔM in H = 0 is within the range of the Meissner effect induced by the possible residual field, suggesting that the spontaneous magnetization, if it exists, is below the experimental accuracy. This result is in agreement with the results of μSR experiments, in which no spontaneous magnetic field has been observed in the superconducting state.