The present invention provides a transdermal sensor for detecting a concentration of a hypodermal target molecule, comprising: a substrate a plurality of microneedles fixed on said substrate a signal processing unit, which is electrically connected to said microneedles and a power supply unit for providing the working power. The transdermal sensor of the present invention detects long-term, real-time concentration of a hypodermal target molecule for a doctor to evaluate a physiological status of an user with minimal invasive piercing and pain.
