A sensing sensor includes a wiring board, a piezoelectric resonator, a channel forming member, a channel, an effluent channel, a capillary member, and an absorbing member. The effluent channel is disposed at a downstream side of the channel. The effluent channel is configured to discharge the sample solution inside of the channel by capillarity. The capillary member is disposed at a downstream side of the effluent channel in contact with the sample solution flowing through an inside of the effluent channel. The capillary member is configured to cause the sample solution to flow through by the capillarity. The absorbing member is disposed at a downstream side of the capillary member. The absorbing member is configured to absorb the sample solution flowing through the capillary member.