The invention discloses a fuel vapor processing apparatus. The apparatus can control correction of air-fuel ratio in an in-timely manner by slowering valve opening of a flow control valve when a vapor passage is open, and suppresses disorder of the air-fuel ratio of an engine when the steam passage is open. The apparatus enables a vapor fuel inside a fuel tank (15) to be absorbed to an absorption tank (21), supplies the vapor fuel which is absorbed to the absorption tank (21) to an engine body (11) and performs blowing. The fuel vapor processing apparatus includes: a lock valve (24) which inserts to a vapor path (22) which makes the absorption tank (21) and the fule tank (15) communicate, the lock valve (24) being intended for controlling on and off of the vapor path (22); and a control part (16a) for controlling the starting speed of the valve opening, the control valve (16a) setting the starting speed of the valve opening when the lock valve (24) opens the valve as a pre-determined amount speed for opening the lock valve (24) each time with a period longer than the period that is controlled by an air-fuel ratio feedback of the engine.