To provide a diaphragm type pump device which easily changes characteristics of flow rate and flow pressure.

This diaphragm type pump device has switching means 42, 44 capable of switching between a compression chamber parallel connection condition in which fluid taken into one compression chamber from a flow-in port 29 is discharged from a discharge port 38 through one fluid passage 37 and fluid taken into the other compression chamber 28A from a flow-in port 41 is discharged from the discharge port 38 through the other fluid passage 39, and a compression chamber series connection condition in which fluid taken into one compression chamber from the flow-in port 29 is discharged from the discharge port 38 through the other compression chamber 28A.