In VF-MB1 instruction manual "9.3 Compliance with safety standards" on page I-8, there is a description that safety function of VF-MB1 has been certified by certification organization.
However, some products sold before April 2011 was models before certified.  

We have confirmed all VF-MB1 models can meet the level of safety requirement (STO function). However, If you want a certified model, please contact with local Toshiba inverter distributor to receive return instructions and a free replacement VF-MB1 model.