To provide a squarylium compound forming a metal complex, expressed by the general formula (I): where R1 and R2 are the same or different and each of R1 and R2 represents a substituted or unsubstituted alkyl, aralkyl, aryl, or heterocyclic group; Q represents a metal atom having coordinating ability; q represents 2 or 3; R3 represents a substituted or unsubstituted aralkyl, or aryl group; R4 represents a substituted or unsubstituted alkyl, aralkyl, or aryl group,’ R5 represents a hydrogen atom, or substituted or unsubstituted alkyl, aralkyl, or aryl group; R6 represents a halogen atom, nitro group, cyano group, or substituted or unsubstituted alkyl, aralkyl, aryl, or alkoxy group; p represents any integer ranging from 0 to 4; and RGs are the same or different and any adjacently located two R6s optionally form a substituted or unsubstituted aromatic ring together with two adjacent carbon atoms when p is 2, 3 or 4.