PURPOSE: To make a first and a second vortex type compression pump compact for lightening by improving the structure of a first or a fifth main flow passage so as to improve the compression efficiency effectively.

CONSTITUTION: Multiple blades 42, 72, facing to a first and a fifth main flow passages 28a-28c, 57a, 57b are projected radially in the peripheral parts 41a, 71a of a first and a second impellers 22, 52 of a first and a second vortex type compression pumps VA1-VA3, VB1, VB2. Cross section area of each main flow passage 28a-28c, 57a, 57b is reduced gradually from the suction ports 34, 63 side to the discharge ports 35, 64 side.