Abstract: A carboxylic acid compound having cyclopropane ring(s) of the formula (I): wherein R is alkyl or alkenyl optionally having one or more 1,2-cyclopropylene in a carbon chain and/or optionally having cyclopropyl at the end of a chain,X is a single bond or alkylene, wherein the total number of carbon less the number of cyclopropane ring is 10-25, and a pharmaceutically acceptable salt thereof are provided. The compound (I) shows an LTP-like potentiation of synaptic transmission, allows slow metabolism in the living body, show a stable LTP-like potentiation of synaptic transmission, and is useful as an agent for LTP-like potentiation of synaptic transmission, a cognition-enhancing drug or an agent for the prophylaxis and treatment of dementia, a learning and memory disorder and a neurotransmitter release disorder.