A method for producing cAMP using a chimeric olfactory receptor. The method includes a step of preparing a reaction system comprising a first layer, a lipid bilayer membrane, and a second layer, and a step of supplying a chemical substance which stimulates the chimeric olfactory receptor to the first layer so as to produce the cAMP from ATP. The lipid bilayer membrane includes the chimeric olfactory receptor and adenylate cyclase. The chimeric olfactory receptor penetrates the lipid bilayer membrane. The second layer contains ATP and a G protein. The G protein is placed in the vicinity of one end of the chimeric olfactory receptor. The chimeric olfactory receptor is derived from a mouse olfactory receptor and the N-terminal of the chimeric olfactory receptor is modified with an amino acid sequence.