The invention provides a thermal type flow meter which has a high reliability and a low cost. In a thermal type flow meter provided with a flow rate detecting element in which at least a heat generating resistor and a lead electrode are formed on a surface of a tabular substrate, and a support body in which a concave portion accommodating the flow rate detecting element is formed on a surface, and in which the flow rate detecting element is firmly fixed and accommodated by an adhesive agent in a back surface of the tabular substrate and a part of a bottom surface of the concave portion, an approximately straight discharge groove which is deeper than a bottom surface of the concave portion and passes through both end surfaces in upward and downward sides of the concave portion is formed from the upstream side of the support body concave portion to the downstream side, between the cavity of the tabular substrate and the back surface region of the tabular substrate in which the lead electrode is formed. Accordingly, it is possible to achieve the thermal type flow meter which has the high reliability and the low cost.