A micropump check valve device which can be designed thin with good
assemblability and applied with urging force. The micropump check valve
device includes an upstream side member having a small-bore hole for
passing therethrough a fluid, a downstream side member having a
large-bore hole for passing therethrough the fluid, and a valve member
having a valve mechanism sandwiched between the upstream side member and
the downstream side member. The valve mechanism includes a passing hole
formed in correspondence to a position and a size of the large-bore hole
in the downstream side member, a contacting part formed inside the
passing hole in correspondence to the position and size of the small-bore
hole in the upstream side member thereby to close the small-bore hole,
and supporting parts formed to bridge across the passing hole to support
the contacting part. The valve member has a greater linear expansion
coefficient than the upstream side and downstream side members.