PURPOSE: To provide the titled preventive and remedy containing a specific cyclic compound as an active component, and capable of remarkably suppressing the contraction of the basilar vessel caused by oxyhemoglobin.

CONSTITUTION: The objective preventive and remedy for cerebrovascular twitch can be prepared by using the compound of formula I or formula II or its salt as an active component. The compound of formula I or formula II can be administered singly or in combination with a carrier in the form of tablet, capsule, powder, injection by oral or parenteral administration or direct application to the diseased part, or by intraspinal administration using a catheter. Dose; 0.01W 3.0g, preferably 0.1W1.5g per dose. The compound of formula I used as an active component can be separated from Cladiella sp. The compound of formula IIcan be prepared by hydrolyzing the compound of formula I e.g. with NaOH, etc.