The simultaneously inhibit both ASIC1a and NMDA receptors are involved in neurodegenerative diseases such as to provide new compounds useful in the prevention and treatment of neurological disorders variety. (Wherein, X 1 is a halogen atom, R 1 is shows an aralkyl group which may have a substituent or an aryl group which may have an alkyl group or a substituted group) biguanide derivative represented by the formula, a hydrate thereof or a salt thereof. The general formula (1)神経変性疾患等に関与しているNMDA受容体及びASIC1aの両者を同時に阻害し、種々の神経系疾患の予防及び治療に有用な新たな化合物を提供する。(式中、X1はハロゲン原子を示し、R1はアルキル基、置換基を有していてもよいアリール基又は置換基を有していてもよいアラルキル基を示す)で表されるビグアニド誘導体、その塩又はそれらの水和物。一般式(1)
