To provide a compound useful for producing piperidine derivatives useful for an antihistamine agent, an antiallergic agent or a bronchodilator.

The piperidine formyl phenyl alcohol compound or piperidine formyl phenyl ketone compound is expressed by a specific general formula. A specific piperidine hydroxyethyl phenyl ketone derivative is obtained in the following process, a step preparing phenethyl alcohol by reacting a specific benzeneacetic acid compound with a proper reducing agent, producing a ω-hydroxyethyl phenyl ketone by reacting a ω-halo compound with the phenetyl alcohol in the presence of a proper Lewis acid and then reacting with a specific piperidine compound in the presence of a proper non-nucleophilic reagent.