We have searched for lepton flavor violating semileptonic τ- decays using a data sample of 153.8 fb-1 accumulated with the Belle detector at the KEKB e+e- collider. For the six decay modes studied, the observed yield is compatible with the estimated background and the following upper limits are set at the 90% confidence level: B(τ-→e-η)<2.3×10-7, B(τ-→μ-η)<1.5×10-7, B(τ-→e-π0)<1.9×10-7, B(τ-→μ-π0)<4.1×10-7, B(τ-→e-η′) <10×10-7, and B(τ-→μ-η′)<4.7×10-7. These results are 10 to 64 times more restrictive than previous limits. © 2005 Elsevier B.V. All rights reserved.