NOVELTY - The electrolyzer comprises a set of management parts provided with an electrode plate for performing a seawater electrolysis, a set of connection pipes interconnecting the management parts so that a fluid path is formed with the management parts in a zigzag manner, a set of hydrogen exhaust pipes formed in a blocking plate having an orifice hole to guide the hydrogen generated during the electrolysis process and inhibit the flow of seawater flows to an upper portion, the connection pipe and the hydrogen exhaust pipe connecting the neighboring management parts.    USE - The electrolyzer is useful in an electrolysis device (claimed) that is used to electrolyze the seawater in a ballast tank of a vessel.    ADVANTAGE - The electrolyzer prevents the flux degradation of seawater using the management parts, prevents the scale occurrence due to the degradation of the flux, prevents the degradation of energy efficiency of the electrode, and has excellent performance. The hydrogen generated in the electrolysis process of seawater is not passed through the electrode and is ejected through the orifice hole in the hydrogen exhaust pipe to the upper portion, so that the performance degradation of the electrode due to the contact of the electrode and hydrogen can be prevented. The maintenance and repair work of the inner portion of the management part can be performed in convenient manner.    DETAILED DESCRIPTION - The electrolyzer comprises a set of management parts provided with an electrode plate for performing a seawater electrolysis, a set of connection pipes interconnecting the management parts by connecting an end portion of the management parts, so that a fluid path is formed with the management parts in a zigzag manner, a set of hydrogen exhaust pipes formed in a blocking plate having an orifice hole to guide the hydrogen generated during the electrolysis process and inhibit the flow of seawater flows to an upper portion, the connection pipe and the hydrogen exhaust pipe connecting the neighboring management parts in an inside area of the management parts and inhibiting the volume increase of the electrolyzer. A cover is arranged in the management parts and enables the opening and closing of the management parts, where the management parts are provided with a lamination.