PURPOSE: To inexpensively enhance pump efficiency of a side flow type turbine pump with simple constitution.

CONSTITUTION: Plural recessed parts 25A and 25B are arranged on the obverse and reverse of an impeller 21', and a window 22' to secure the flow of fuel between a fuel passage 24A and a fuel passage 24B is opened in a long and narrow (longitudinally long) shape in the radial direction of a rotary shaft 5A. Therefore, since turning flows of fuel oppositely turning by sandwiching the impeller 21' are restrained from interfering with each other over a rotational directional wide range in the recessed parts 25A and 25B while securing the flow of fuel between the fuel passage 24A and the fuel passage 24B, the occurrence of stagnation of fuel can be significantly reduced, so that pump efficiency can be further enhanced.