Simultaneous irradiation effects of He on tungsten blistering with hydrogen and carbon mixed ion beam were investigated. It was found that only 0.1% addition of He ions to 1 keV H and C mixed ion beam (C:0.8-1.0%) reduced (at 473 K) or completely suppressed (at 653 K and 723 K) blister formation. In order to obtain more detailed result, two ion sources were used to irradiate tungsten with H and He ions with different energies. In the He energy of 0.6 keV (1.5 keV H&C),significant blistering was observed, while in the He energies of 1.0 keV and 1.5 keV, blister formation was suppressed. These results suggested that a He bubble layer reduced hydrogen diffusion through the layer. A He bubble size and a volume rate were about 1-2 nm and ~2% at 653 K, respectively. To evaluate T retention in the ITER tungsten wall, this effect should be included.