It is an object of the preset invention to provide an activity measurement molecule necessary for measuring biological reactions or changes in in vivo conditions, and a method for measuring activity using the above activity measurement molecule. It is intended to provide an activity measurement molecule used for simultaneously analyzing multiple biological reactions and/or changes in in vivo conditions, which is characterized in that one or more fluorescent molecule-labeled and/or —unlabeled biomolecules used as targets of the biological reactions or changes in in vivo conditions bind onto a quantum dot, and a method for simultaneously analyzing multiple biological reactions and/or changes in in vivo conditions using the above activity measurement molecule.
